Pub Date : 2024-04-11DOI: 10.1088/1361-6641/ad3a92
Zhenxing Lv, Zhefu Liao, Shengjun Zhou
Increasing the reflection of p-side is an effective way to improve the optoelectronic performance of flip-chip light-emitting diodes (FCLEDs). Here, we propose a full-coverage Al reflector (FAR) and a highly reflective Ni/Rh p-electrode to enhance the performance of deep ultraviolet (DUV) FCLEDs. The physical mechanism for the impact of the FAR and Ni/Rh electrode on the light extraction efficiency (LEE) is discussed theoretically. Simulations demonstrate that the combination of the FAR and Ni/Rh electrode improves the LEEs of transverse electric- and transverse magnetic-polarized light by 13.62% and 27.08%, respectively. At an injection current of 100 mA, the fabricated DUV FCLEDs with FAR and Ni/Rh electrode exhibits an external quantum efficiency of 4.01% and a wall plugging efficiency of 2.92%, which are 16.85% and 13.18% higher than those of conventional DUV FCLEDs, respectively. These results support the promise of the FAR and Ni/Rh electrode for high-power DUV LED applications.
提高 p 面的反射率是改善倒装芯片发光二极管（FCLED）光电性能的有效方法。在此，我们提出了一种全覆盖铝反射器（FAR）和一种高反射镍/铑对电极，以提高深紫外（DUV）FCLED 的性能。理论上讨论了 FAR 和 Ni/Rh 电极对光萃取效率（LEE）影响的物理机制。模拟结果表明，结合使用 FAR 和 Ni/Rh 电极，横向电偏振光和横向磁偏振光的萃取效率分别提高了 13.62% 和 27.08%。在注入电流为 100 mA 时，使用 FAR 和 Ni/Rh 电极制造的 DUV FCLED 的外部量子效率为 4.01%，堵壁效率为 2.92%，分别比传统 DUV FCLED 高出 16.85% 和 13.18%。这些结果支持了 FAR 和 Ni/Rh 电极在高功率 DUV LED 应用中的前景。
{"title":"Enhanced efficiency of deep ultraviolet light-emitting diodes utilizing full-coverage Al reflector and highly reflective Ni/Rh p-electrode","authors":"Zhenxing Lv, Zhefu Liao, Shengjun Zhou","doi":"10.1088/1361-6641/ad3a92","DOIUrl":"https://doi.org/10.1088/1361-6641/ad3a92","url":null,"abstract":"Increasing the reflection of p-side is an effective way to improve the optoelectronic performance of flip-chip light-emitting diodes (FCLEDs). Here, we propose a full-coverage Al reflector (FAR) and a highly reflective Ni/Rh p-electrode to enhance the performance of deep ultraviolet (DUV) FCLEDs. The physical mechanism for the impact of the FAR and Ni/Rh electrode on the light extraction efficiency (LEE) is discussed theoretically. Simulations demonstrate that the combination of the FAR and Ni/Rh electrode improves the LEEs of transverse electric- and transverse magnetic-polarized light by 13.62% and 27.08%, respectively. At an injection current of 100 mA, the fabricated DUV FCLEDs with FAR and Ni/Rh electrode exhibits an external quantum efficiency of 4.01% and a wall plugging efficiency of 2.92%, which are 16.85% and 13.18% higher than those of conventional DUV FCLEDs, respectively. These results support the promise of the FAR and Ni/Rh electrode for high-power DUV LED applications.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"78 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140608629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, p-n junction vertical gate (JVG) and polarization junction vertical gate (PVG) structures are for the first time proposed to improve the performance of GaN-based enhancement-mode (E-mode) high electron mobility transistor (HEMT) devices. Compared with the control group featuring the vertical gate structure, a highly improved threshold voltage (Vth) and breakdown voltage (BV) are achieved with the assistance of the extended depletion regions formed by inserting single or composite interlayers. The structure dimensions and physical parameters for device interlayers are optimized by TCAD simulation to adjust the spatial electric field distribution and hence improve the device off-state characteristics. The optimal JVG-HEMT device can reach a Vth of 3.4 V, a low on-state resistance (Ron) of 0.64 mΩ cm2, and a BV of 1245 V, while the PVG-HEMT device exhibits a Vth of 3.7 V, an Ron of 0.65 mΩ cm2, and a BV of 1184 V, which could be further boosted when an additional field plate design is employed. Thus, the figure-of-merit value of JVG- and PVG-HEMT devices rise to 2.4 and 2.2 GW cm−2, respectively, much higher than that for the VG-HEMT control group (1.0 GW cm−2). This work provides a novel technical approach to realize higher-performance E-mode HEMTs.
{"title":"Performance improvement of enhancement-mode GaN-based HEMT power devices by employing a vertical gate structure and composite interlayers*","authors":"Zhonghao Sun, Jianxun Dai, Huolin Huang, Nan Sun, Jiayu Zhang, Yun Lei, Dawei Li, Kaiming Ma, Huimin Yu, Yanhong Liu, Hui Huang, Yung C Liang","doi":"10.1088/1361-6641/ad31c5","DOIUrl":"https://doi.org/10.1088/1361-6641/ad31c5","url":null,"abstract":"In this work, p-n junction vertical gate (JVG) and polarization junction vertical gate (PVG) structures are for the first time proposed to improve the performance of GaN-based enhancement-mode (E-mode) high electron mobility transistor (HEMT) devices. Compared with the control group featuring the vertical gate structure, a highly improved threshold voltage (<italic toggle=\"yes\">V</italic>\u0000<sub>th</sub>) and breakdown voltage (<italic toggle=\"yes\">BV</italic>) are achieved with the assistance of the extended depletion regions formed by inserting single or composite interlayers. The structure dimensions and physical parameters for device interlayers are optimized by TCAD simulation to adjust the spatial electric field distribution and hence improve the device off-state characteristics. The optimal JVG-HEMT device can reach a <italic toggle=\"yes\">V</italic>\u0000<sub>th</sub> of 3.4 V, a low on-state resistance (<italic toggle=\"yes\">R</italic>\u0000<sub>on</sub>) of 0.64 mΩ cm<sup>2</sup>, and a <italic toggle=\"yes\">BV</italic> of 1245 V, while the PVG-HEMT device exhibits a <italic toggle=\"yes\">V</italic>\u0000<sub>th</sub> of 3.7 V, an <italic toggle=\"yes\">R</italic>\u0000<sub>on</sub> of 0.65 mΩ cm<sup>2</sup>, and a <italic toggle=\"yes\">BV</italic> of 1184 V, which could be further boosted when an additional field plate design is employed. Thus, the figure-of-merit value of JVG- and PVG-HEMT devices rise to 2.4 and 2.2 GW cm<sup>−2</sup>, respectively, much higher than that for the VG-HEMT control group (1.0 GW cm<sup>−2</sup>). This work provides a novel technical approach to realize higher-performance E-mode HEMTs.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"70 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-14DOI: 10.1088/1361-6641/ad2ec6
M Derya Alyörük
The electronic transport characteristics of tungsten disulfide (WS2) sheets are studied using the ensemble Monte Carlo technique in the presence of intrinsic scattering mechanisms only. The transport properties of the material are obtained in a two-valley model where intra- and inter-valley scatterings are considered in K and Q valleys. The velocity overshoot effect is observed for some applied field values. Negative differential phenomena are seen for some values of the energy difference between K and Q valleys (ΔEKQ), therefore ΔEKQ and the effective mass of carriers in the Q valley has a critical role in the transport and mobility characteristics of WS2. The mobility of carriers is calculated as a function of temperature and the results are compatible with some existing theoretical and experimental predictions.
在仅存在内在散射机制的情况下，使用集合蒙特卡罗技术研究了二硫化钨（WS2）薄片的电子传输特性。材料的输运特性是在双谷模型中获得的，其中考虑了 K 谷和 Q 谷中的谷内和谷间散射。在某些外加磁场值中观察到了速度过冲效应。在 K 谷和 Q 谷之间能量差（ΔEKQ）的某些值上会出现负差分现象，因此ΔEKQ 和 Q 谷中载流子的有效质量对 WS2 的传输和迁移率特性起着至关重要的作用。我们计算了载流子的迁移率与温度的函数关系，结果与现有的一些理论和实验预测相符。
{"title":"Electronic transport properties of WS2 using ensemble Monte Carlo method","authors":"M Derya Alyörük","doi":"10.1088/1361-6641/ad2ec6","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2ec6","url":null,"abstract":"The electronic transport characteristics of tungsten disulfide (WS<sub>2</sub>) sheets are studied using the ensemble Monte Carlo technique in the presence of intrinsic scattering mechanisms only. The transport properties of the material are obtained in a two-valley model where intra- and inter-valley scatterings are considered in K and Q valleys. The velocity overshoot effect is observed for some applied field values. Negative differential phenomena are seen for some values of the energy difference between K and Q valleys (<inline-formula>\u0000<tex-math><?CDATA $Delta E_mathrm{KQ}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi mathvariant=\"normal\">Δ</mml:mi><mml:msub><mml:mi>E</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">K</mml:mi><mml:mi mathvariant=\"normal\">Q</mml:mi></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"sstad2ec6ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>), therefore <inline-formula>\u0000<tex-math><?CDATA $Delta E_mathrm{KQ}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi mathvariant=\"normal\">Δ</mml:mi><mml:msub><mml:mi>E</mml:mi><mml:mrow><mml:mi mathvariant=\"normal\">K</mml:mi><mml:mi mathvariant=\"normal\">Q</mml:mi></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"sstad2ec6ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> and the effective mass of carriers in the Q valley has a critical role in the transport and mobility characteristics of WS<sub>2</sub>. The mobility of carriers is calculated as a function of temperature and the results are compatible with some existing theoretical and experimental predictions.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"194 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-12DOI: 10.1088/1361-6641/ad2bac
Alexander K Sten, Kevin M Roccapriore, Brian Squires, Chris Littler, A J Syllaios, Usha Philipose
The present work highlights the role of halogen compounds in modifying the shape of the InSb nanostructures, while maintaining a high crystalline quality of the nanostructures. One-dimensional (1D) nanowires (NWs) and two-dimensional (2D) nanoplatelets (NPLs) were synthesized by ambient pressure chemical vapor deposition. Our experimental results suggest that at a critical growth temperature of 512 ∘C, InSb NWs grow by the traditional vapor–liquid–solid growth mechanism when gold (Au) nanoparticles are used to initiate growth on an InSb film. The resulting NWs were found to have a cylindrical or tapered shape, were of high crystalline quality, and had stoichiometric composition. In the presence of halogen precursors, a change in morphology was observed and the resulting nanostructures were 2D NPLs and faceted NWs. Using existing models of crystal growth and concepts of volume, surface and edge energies, the experimental results are explained on the basis of chlorine atoms adsorbed on the wide or narrow facets of a nanocrystal, initiating nucleation and facilitating NPL or faceted NW formation. The incorporation of the chlorine atoms add a new degree of freedom to CVD synthesis of nanostructures and the results are promising for the controlled growth of novel 1D and 2D nanostructures for nano-electronic devices.
{"title":"Influence of halogen precursors on the growth of InSb nanostructures","authors":"Alexander K Sten, Kevin M Roccapriore, Brian Squires, Chris Littler, A J Syllaios, Usha Philipose","doi":"10.1088/1361-6641/ad2bac","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2bac","url":null,"abstract":"The present work highlights the role of halogen compounds in modifying the shape of the InSb nanostructures, while maintaining a high crystalline quality of the nanostructures. One-dimensional (1D) nanowires (NWs) and two-dimensional (2D) nanoplatelets (NPLs) were synthesized by ambient pressure chemical vapor deposition. Our experimental results suggest that at a critical growth temperature of 512 <sup>∘</sup>C, InSb NWs grow by the traditional vapor–liquid–solid growth mechanism when gold (Au) nanoparticles are used to initiate growth on an InSb film. The resulting NWs were found to have a cylindrical or tapered shape, were of high crystalline quality, and had stoichiometric composition. In the presence of halogen precursors, a change in morphology was observed and the resulting nanostructures were 2D NPLs and faceted NWs. Using existing models of crystal growth and concepts of volume, surface and edge energies, the experimental results are explained on the basis of chlorine atoms adsorbed on the wide or narrow facets of a nanocrystal, initiating nucleation and facilitating NPL or faceted NW formation. The incorporation of the chlorine atoms add a new degree of freedom to CVD synthesis of nanostructures and the results are promising for the controlled growth of novel 1D and 2D nanostructures for nano-electronic devices.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"107 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-08DOI: 10.1088/1361-6641/ad2b07
Kihwan Choi, James Jungho Pak
In this study, a solution-processed bilayer structure ZrO2/SnO2 resistive switching (RS) random access memory (RRAM) is presented for the first time. The precursors of SnO2 and ZrO2 are Tin(Ⅱ) acetylacetonate (Sn(AcAc)2) and zirconium acetylacetonate (Zr(C5H7O2)4), respectively. The top electrode was deposited with Ti using an E-beam evaporator, and the bottom electrode used an indium–tin–oxide glass wafer. We created three devices: SnO2 single-layer, ZrO2 single-layer, and ZrO2/SnO2 bilayer devices, to compare RS characteristics such as the I–V curve and endurance properties. The SnO2 and ZrO2 single-layer devices showed on/off ratios of approximately 2 and 51, respectively, along with endurance switching cycles exceeding 50 and 100 DC cycles. The bilayer device attained stable RS characteristics over 120 DC endurance switching cycles and increased on/off ratio ∼2.97 × 102. Additionally, the ZrO2/SnO2 bilayer bipolar switching mechanism was explained by considering the Gibbs free energy (ΔGo) difference in the ZrO2 and SnO2 layers, where the formation and rupture of conductive filaments were caused by oxygen vacancies. The disparity in the concentration of oxygen vacancies, as indicated by the Gibbs free energy difference between ZrO2 (ΔGo = −1100 kJ mol−1) and SnO2 (ΔGo = −842.91 kJ mol−1) implied that ZrO2 exhibited a higher abundance of oxygen vacancies compared to SnO2, resulting in improved endurance and on/off ratio. X-ray photoelectron spectroscopy analyzed oxygen vacancies in ZrO2 and SnO2 thin films. The resistance switching characteristics were improved due to the bilayer structure, which combines a higher oxygen vacancy concentration in one layer with a lower oxygen vacancy concentration in the switching layer. This configuration reduces the escape of oxygen vacancies to the electrode during RS.
{"title":"Improved resistive switching characteristics of solution processed ZrO2/SnO2 bilayer RRAM via oxygen vacancy differential","authors":"Kihwan Choi, James Jungho Pak","doi":"10.1088/1361-6641/ad2b07","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2b07","url":null,"abstract":"In this study, a solution-processed bilayer structure ZrO<sub>2</sub>/SnO<sub>2</sub> resistive switching (RS) random access memory (RRAM) is presented for the first time. The precursors of SnO<sub>2</sub> and ZrO<sub>2</sub> are Tin(Ⅱ) acetylacetonate (Sn(AcAc)<sub>2</sub>) and zirconium acetylacetonate (Zr(C<sub>5</sub>H<sub>7</sub>O<sub>2</sub>)<sub>4</sub>), respectively. The top electrode was deposited with Ti using an E-beam evaporator, and the bottom electrode used an indium–tin–oxide glass wafer. We created three devices: SnO<sub>2</sub> single-layer, ZrO<sub>2</sub> single-layer, and ZrO<sub>2</sub>/SnO<sub>2</sub> bilayer devices, to compare RS characteristics such as the <italic toggle=\"yes\">I</italic>–<italic toggle=\"yes\">V</italic> curve and endurance properties. The SnO<sub>2</sub> and ZrO<sub>2</sub> single-layer devices showed on/off ratios of approximately 2 and 51, respectively, along with endurance switching cycles exceeding 50 and 100 DC cycles. The bilayer device attained stable RS characteristics over 120 DC endurance switching cycles and increased on/off ratio ∼2.97 × 10<sup>2</sup>. Additionally, the ZrO<sub>2</sub>/SnO<sub>2</sub> bilayer bipolar switching mechanism was explained by considering the Gibbs free energy (Δ<italic toggle=\"yes\">G</italic>\u0000<sup>o</sup>) difference in the ZrO<sub>2</sub> and SnO<sub>2</sub> layers, where the formation and rupture of conductive filaments were caused by oxygen vacancies. The disparity in the concentration of oxygen vacancies, as indicated by the Gibbs free energy difference between ZrO<sub>2</sub> (Δ<italic toggle=\"yes\">G</italic>\u0000<sup>o</sup> = −1100 kJ mol<sup>−1</sup>) and SnO<sub>2</sub> (Δ<italic toggle=\"yes\">G</italic>\u0000<sup>o</sup> = −842.91 kJ mol<sup>−1</sup>) implied that ZrO<sub>2</sub> exhibited a higher abundance of oxygen vacancies compared to SnO<sub>2</sub>, resulting in improved endurance and on/off ratio. X-ray photoelectron spectroscopy analyzed oxygen vacancies in ZrO<sub>2</sub> and SnO<sub>2</sub> thin films. The resistance switching characteristics were improved due to the bilayer structure, which combines a higher oxygen vacancy concentration in one layer with a lower oxygen vacancy concentration in the switching layer. This configuration reduces the escape of oxygen vacancies to the electrode during RS.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"21 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-08DOI: 10.1088/1361-6641/ad2a7f
Lijian Guo, Feng Zhou, Weizong Xu, Fangfang Ren, Dong Zhou, Dunjun Chen, Rong Zhang, Youdou Zheng, Hai Lu
Bonding pad over active (BPOA) layout, which stacks traditional horizontal structure pad electrodes vertically above the active area, is an area-effective device architecture and packaging-enabled solution for GaN-based high electron mobility transistors (HEMTs). In this work, the dynamic switching and electric field distribution of such layout, as well as associated capacitance–voltage and trapping characteristics, are comprehensively studied on D-mode GaN-on-sapphire HEMT by performing numerical simulations. In terms of different pad electrodes covering the active area, BPOA is composed of various structures such as gate-related and drain-related BPOAs (i.e. G-BPOA and D-BPOA), among which G-BPOA exhibits inferior switching characteristics due to the additional introduction of Miller capacitance that prolongs the device switching, while breakdown voltage of D-BPOA is 400–900 V lower than other BPOA counterparts due to the interplay between D-BPOA and the drain electrode. Furthermore, the effects of trap capture cross section and trap density on switching characteristics are evaluated. These results highlight the differences in electrical characteristics of various structures within the BPOA layout, and provide valuable insights into BPOA device design and performance improvement.
{"title":"Insights into dynamic switching behavior and electric field distribution of depletion-mode GaN HEMT with bonding pad over active layout","authors":"Lijian Guo, Feng Zhou, Weizong Xu, Fangfang Ren, Dong Zhou, Dunjun Chen, Rong Zhang, Youdou Zheng, Hai Lu","doi":"10.1088/1361-6641/ad2a7f","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2a7f","url":null,"abstract":"Bonding pad over active (BPOA) layout, which stacks traditional horizontal structure pad electrodes vertically above the active area, is an area-effective device architecture and packaging-enabled solution for GaN-based high electron mobility transistors (HEMTs). In this work, the dynamic switching and electric field distribution of such layout, as well as associated capacitance–voltage and trapping characteristics, are comprehensively studied on D-mode GaN-on-sapphire HEMT by performing numerical simulations. In terms of different pad electrodes covering the active area, BPOA is composed of various structures such as gate-related and drain-related BPOAs (i.e. G-BPOA and D-BPOA), among which G-BPOA exhibits inferior switching characteristics due to the additional introduction of Miller capacitance that prolongs the device switching, while breakdown voltage of D-BPOA is 400–900 V lower than other BPOA counterparts due to the interplay between D-BPOA and the drain electrode. Furthermore, the effects of trap capture cross section and trap density on switching characteristics are evaluated. These results highlight the differences in electrical characteristics of various structures within the BPOA layout, and provide valuable insights into BPOA device design and performance improvement.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"72 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-07DOI: 10.1088/1361-6641/ad2d62
Takahiro Fujisawa, Nan Hu, Tomoki Kojima, Takashi Egawa, Makoto Miyoshi
We investigated the GaInN-based photoelectric transducers (PTs) aiming at the application to optical wireless power transmission systems. A PT device structure with Ga0.9In0.1N multiple-quantum-wells (MQWs) as a light absorption layer was grown on a free-standing GaN substrate by metalorganic chemical vapor deposition and subjected to the device fabrication. The PT performance was evaluated via the two-terminal current-density vs. voltage characteristics taken under a monochromatic light illumination. The fabricated PT devices exhibited a high open-circuit voltage of approximately 2.3 V and a high shunt resistance of 41 kΩcm2, thanks to its good material qualities. In addition, its surface reflection was markedly suppressed by an adoption of a wet surface treatment and an anti-reflection coating, resulting in a high external quantum efficiency of 90% and a high short-circuit current density of 1.4 mAcm−2. Through the above investigation, a high power-conversion efficiency as great as 43.7% was achieved for the GaInN MQW PTs at a light illumination with 390 nm in wavelength and 5 mWcm−2 in optical power density.
{"title":"Over 43%-power-efficiency GaInN-based photoelectric transducer on free-standing GaN substrate for optical wireless power transmission system","authors":"Takahiro Fujisawa, Nan Hu, Tomoki Kojima, Takashi Egawa, Makoto Miyoshi","doi":"10.1088/1361-6641/ad2d62","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2d62","url":null,"abstract":"We investigated the GaInN-based photoelectric transducers (PTs) aiming at the application to optical wireless power transmission systems. A PT device structure with Ga<sub>0.9</sub>In<sub>0.1</sub>N multiple-quantum-wells (MQWs) as a light absorption layer was grown on a free-standing GaN substrate by metalorganic chemical vapor deposition and subjected to the device fabrication. The PT performance was evaluated via the two-terminal current-density vs. voltage characteristics taken under a monochromatic light illumination. The fabricated PT devices exhibited a high open-circuit voltage of approximately 2.3 V and a high shunt resistance of 41 kΩcm<sup>2</sup>, thanks to its good material qualities. In addition, its surface reflection was markedly suppressed by an adoption of a wet surface treatment and an anti-reflection coating, resulting in a high external quantum efficiency of 90% and a high short-circuit current density of 1.4 mAcm<sup>−2</sup>. Through the above investigation, a high power-conversion efficiency as great as 43.7% was achieved for the GaInN MQW PTs at a light illumination with 390 nm in wavelength and 5 mWcm<sup>−2</sup> in optical power density.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"49 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Organic light-emitting diodes (OLEDs) have become one of the mainstream lighting and display technologies. The vacuum thermal evaporation is the most widely adopted method for the preparation of organic and metal materials of OLEDs. The thermal deposition of the commonly used silver (Ag) and aluminum (Al) electrodes requires high temperature and long time, which greatly increases the cost of the fabricating process. Therefore, we selected silver oxide (Ag2O) powder instead of Ag pellets as the precursor for evaporating Ag electrodes. Compared to Ag pellets and Al wires, Ag2O-based Ag electrode need lower evaporation temperature and shorter preheating time. In addition, the agglomeration phenomenon on the surface of the Ag2O-based Ag film is prevented, which also increases the carrier concentration of Ag electrode. Moreover, by doping bathophenanthroline (Bphen) in Ag2O powders, the phenanthroline-metal (Bphen-Ag) complexes with higher electron mobility and stronger electron injecting ability can be achieved. We applied Ag2O-based Ag electrode and 10 wt.% Ag2O-based Ag:Bphen as electron injection layer to achieve high-efficiency red phosphorescent inverted OLEDs, with the maximum current efficiency, external quantum efficiency, and power efficiency of 17.79 cd A−1, 20.71%, and 12.14 lm W−1, respectively. This method provides a new strategy for preparing highly efficient inverted red OLED devices.
{"title":"Study on low-temperature evaporation of Ag2O-based Ag electrode and electron injection layer and their application in OLEDs","authors":"Yachen Xu, Jialu Gu, Lulu Zhou, Bingjia Zhao, Yangyang Zhu, Wei Shi, Bin Wei","doi":"10.1088/1361-6641/ad2d63","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2d63","url":null,"abstract":"Organic light-emitting diodes (OLEDs) have become one of the mainstream lighting and display technologies. The vacuum thermal evaporation is the most widely adopted method for the preparation of organic and metal materials of OLEDs. The thermal deposition of the commonly used silver (Ag) and aluminum (Al) electrodes requires high temperature and long time, which greatly increases the cost of the fabricating process. Therefore, we selected silver oxide (Ag<sub>2</sub>O) powder instead of Ag pellets as the precursor for evaporating Ag electrodes. Compared to Ag pellets and Al wires, Ag<sub>2</sub>O-based Ag electrode need lower evaporation temperature and shorter preheating time. In addition, the agglomeration phenomenon on the surface of the Ag<sub>2</sub>O-based Ag film is prevented, which also increases the carrier concentration of Ag electrode. Moreover, by doping bathophenanthroline (Bphen) in Ag<sub>2</sub>O powders, the phenanthroline-metal (Bphen-Ag) complexes with higher electron mobility and stronger electron injecting ability can be achieved. We applied Ag<sub>2</sub>O-based Ag electrode and 10 wt.% Ag<sub>2</sub>O-based Ag:Bphen as electron injection layer to achieve high-efficiency red phosphorescent inverted OLEDs, with the maximum current efficiency, external quantum efficiency, and power efficiency of 17.79 cd A<sup>−1</sup>, 20.71%, and 12.14 lm W<sup>−1</sup>, respectively. This method provides a new strategy for preparing highly efficient inverted red OLED devices.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"53 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-04DOI: 10.1088/1361-6641/ad2b0b
Keerthana C S, Anjana S Nair, Sreepriya K, Jiya James, Santhosh Kumar, N V Unnikrishnan, Saritha A C
Gallium oxide (Ga2O3) is a transparent material with high absorption in the UVC region of the electromagnetic spectrum and hence is a very important candidate in the field of short wavelength optical device fabrication. A proper understanding of the different optical parameters is necessary for developing more efficient coatings and devices. In this work, changes in the optical behavior of Ga2O3 thin films due to post-deposition annealing (at temperatures 300 °C–900 °C) are discussed in detail. Structural, surface morphological and compositional modifications of the films are identified using the x-ray diffractometer, scanning electron microscopy and x-ray photoelectron spectrometer techniques, respectively. At 900 °C, a highly stable monoclinic β phase of Ga2O3 is obtained. The optical transmittance spectra acquired using UV–Vis spectroscopy indicate an improved UVC absorbance of the β-Ga2O3 films with an excellent visible transmittance (>80%). The structural transformation from amorphous to crystalline β-Ga2O3 phase and the associated reduction in defect density is found to modify other optical attributes, like the bandgap energy, Urbach energy, dispersion parameters, etc.
氧化镓（Ga2O3）是一种透明材料，在电磁波谱的紫外区具有高吸收率，因此是短波长光学器件制造领域非常重要的候选材料。正确理解不同的光学参数对于开发更高效的涂层和器件十分必要。本研究详细讨论了 Ga2O3 薄膜在沉积后退火（温度为 300 °C-900 °C）过程中的光学行为变化。利用 X 射线衍射仪、扫描电子显微镜和 X 射线光电子能谱仪技术，分别确定了薄膜的结构、表面形态和成分变化。在 900 ℃ 时，获得了高度稳定的 Ga2O3 单斜 β 相。紫外可见光谱法获得的光学透射光谱表明，β-Ga2O3 薄膜的紫外吸收率有所提高，具有极佳的可见光透射率（80%）。从无定形到结晶 β-Ga2O3 相的结构转变以及与之相关的缺陷密度的降低被发现会改变其他光学属性，如带隙能，厄巴赫能，色散参数等。
{"title":"Understanding the effects of annealing induced structural transformations on the UVC absorbance and other optical properties of RF sputter deposited Ga2O3 thin films","authors":"Keerthana C S, Anjana S Nair, Sreepriya K, Jiya James, Santhosh Kumar, N V Unnikrishnan, Saritha A C","doi":"10.1088/1361-6641/ad2b0b","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2b0b","url":null,"abstract":"Gallium oxide (Ga<sub>2</sub>O<sub>3</sub>) is a transparent material with high absorption in the UVC region of the electromagnetic spectrum and hence is a very important candidate in the field of short wavelength optical device fabrication. A proper understanding of the different optical parameters is necessary for developing more efficient coatings and devices. In this work, changes in the optical behavior of Ga<sub>2</sub>O<sub>3</sub> thin films due to post-deposition annealing (at temperatures 300 °C–900 °C) are discussed in detail. Structural, surface morphological and compositional modifications of the films are identified using the x-ray diffractometer, scanning electron microscopy and x-ray photoelectron spectrometer techniques, respectively. At 900 °C, a highly stable monoclinic <italic toggle=\"yes\">β</italic> phase of Ga<sub>2</sub>O<sub>3</sub> is obtained. The optical transmittance spectra acquired using UV–Vis spectroscopy indicate an improved UVC absorbance of the <italic toggle=\"yes\">β</italic>-Ga<sub>2</sub>O<sub>3</sub> films with an excellent visible transmittance (>80%). The structural transformation from amorphous to crystalline <italic toggle=\"yes\">β</italic>-Ga<sub>2</sub>O<sub>3</sub> phase and the associated reduction in defect density is found to modify other optical attributes, like the bandgap energy, Urbach energy, dispersion parameters, etc.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"45 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140314431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-02-28DOI: 10.1088/1361-6641/ad2b08
Gairat Burashev, Batukhan Tatykayev, Matej Baláž, Natalya Khan, Ardak Jumagazieva, Zhanar Iskakbayeva, Anar Seysembekova, Saparbek Tugelbay, Nurshat Turgynbay, Almagul Niyazbayeva, Aleksandr Ilin, Mukhambetkali Burkitbayev, Zhandos Shalabayev
In this work, we have developed a facile, dry, and environmentally friendly mechanochemical method for the synthesis of cadmium sulfide (m-CdS) nanoparticles in a planetary ball mill using non-toxic precursors. Thiourea was for the first time used as a precursor of sulfide ion in room temperature solid state ball milling synthesis. For comparison of the mechanochemical approach with others, cadmium sulfide nanoparticles were also prepared using the solvothermal method (s-CdS). The crystal structure of cadmium sulfide nanoparticles was studied by XRD, the qualitative chemical band properties were examined by Raman scattering and x-ray photoelectron spectroscopy analysis, and particle morphology and microstructure were investigated by scanning electron microscopy and transmission electron microscopy methods. The sizes of the m-CdS nanoparticles had 5–6 nm in diameter, which is 10 times smaller than the diameter of s-CdS nanorods. The photocatalytic activities of as-prepared cadmium sulfide nanoparticles on the dye degradation and hydrogen production by water splitting were evaluated and the antibacterial activities were also tested. The photocatalytic activity of m-CdS was superior to that of s-CdS in the degradation of Orange II under visible light irradiation. Better results for m-CdS were also evidenced in photocatalytic experiments on hydrogen generation. The maximum rate of hydrogen evolution for m-CdS was 191.9 µmolg−1h−1 at the 120th min,while this indicator for s-CdS was only 58.0 µmolg−1h−1 at the same irradiation time.The better effect of m-CdS was evidenced also in an antibacterial study (namely against gram-positive bacteria).
{"title":"The superiority of the photocatalytic and antibacterial performance of mechanochemically synthesized CdS nanoparticles over solvothermal-prepared ones","authors":"Gairat Burashev, Batukhan Tatykayev, Matej Baláž, Natalya Khan, Ardak Jumagazieva, Zhanar Iskakbayeva, Anar Seysembekova, Saparbek Tugelbay, Nurshat Turgynbay, Almagul Niyazbayeva, Aleksandr Ilin, Mukhambetkali Burkitbayev, Zhandos Shalabayev","doi":"10.1088/1361-6641/ad2b08","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2b08","url":null,"abstract":"In this work, we have developed a facile, dry, and environmentally friendly mechanochemical method for the synthesis of cadmium sulfide (m-CdS) nanoparticles in a planetary ball mill using non-toxic precursors. Thiourea was for the first time used as a precursor of sulfide ion in room temperature solid state ball milling synthesis. For comparison of the mechanochemical approach with others, cadmium sulfide nanoparticles were also prepared using the solvothermal method (s-CdS). The crystal structure of cadmium sulfide nanoparticles was studied by XRD, the qualitative chemical band properties were examined by Raman scattering and x-ray photoelectron spectroscopy analysis, and particle morphology and microstructure were investigated by scanning electron microscopy and transmission electron microscopy methods. The sizes of the m-CdS nanoparticles had 5–6 nm in diameter, which is 10 times smaller than the diameter of s-CdS nanorods. The photocatalytic activities of as-prepared cadmium sulfide nanoparticles on the dye degradation and hydrogen production by water splitting were evaluated and the antibacterial activities were also tested. The photocatalytic activity of m-CdS was superior to that of s-CdS in the degradation of Orange II under visible light irradiation. Better results for m-CdS were also evidenced in photocatalytic experiments on hydrogen generation. The maximum rate of hydrogen evolution for m-CdS was 191.9 <italic toggle=\"yes\">µ</italic>molg<sup>−1</sup>h<sup>−1</sup> at the 120th min,while this indicator for s-CdS was only 58.0 <italic toggle=\"yes\">µ</italic>molg<sup>−1</sup>h<sup>−1</sup> at the same irradiation time.The better effect of m-CdS was evidenced also in an antibacterial study (namely against gram-positive bacteria).","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"28 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140005215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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