Pub Date : 2024-03-07DOI: 10.1088/1361-6641/ad3110
Yuan-Ming Liu, Jih-Chao Chiu, Yu-Ciao Chen, Yu-Cheng Fan, Rong-Wei Ma, Chia-Chun Yen, Tsang-Long Chen, C. Chou, Chee Wee Liu
Flow rate effects of the silane (SiH4) and ammonia (NH3) on the top gate insulator and the cap layer in self-aligned top-gate amorphous InGaZnO thin film transistors are investigated. The hydrogen density increases with increasing SiH4 and NH3 flow rates. Hydrogen passivation can improve the field-effect mobility, subthreshold swing (S.S.), hysteresis. The positive bias instability is also improved by hydrogen incorporation. However, the overabundance of hydrogen causes the significant negative threshold voltage shift under negative bias illumination stress (NBIS). Moreover, the most deteriorated S.S. and hysteresis shift after NBIS occur in the TFT with the most hydrogen source.
{"title":"Enhancements of electrical properties and positive bias instability in self-aligned top-gate a-IGZO TFTs by hydrogen incorporation","authors":"Yuan-Ming Liu, Jih-Chao Chiu, Yu-Ciao Chen, Yu-Cheng Fan, Rong-Wei Ma, Chia-Chun Yen, Tsang-Long Chen, C. Chou, Chee Wee Liu","doi":"10.1088/1361-6641/ad3110","DOIUrl":"https://doi.org/10.1088/1361-6641/ad3110","url":null,"abstract":"\u0000 Flow rate effects of the silane (SiH4) and ammonia (NH3) on the top gate insulator and the cap layer in self-aligned top-gate amorphous InGaZnO thin film transistors are investigated. The hydrogen density increases with increasing SiH4 and NH3 flow rates. Hydrogen passivation can improve the field-effect mobility, subthreshold swing (S.S.), hysteresis. The positive bias instability is also improved by hydrogen incorporation. However, the overabundance of hydrogen causes the significant negative threshold voltage shift under negative bias illumination stress (NBIS). Moreover, the most deteriorated S.S. and hysteresis shift after NBIS occur in the TFT with the most hydrogen source.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140260874","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/ad3112
Nengtao Wu, Zhiheng Xing, L. Luo, Guoqiang Li
In this letter, a p-GaN gate high-electron-mobility transistor (HEMT) with a high threshold voltage and better gate reliability was demonstrated by using selective plasma oxidation (SPO) and an additional low-temperature annealing step before gate metal is evaporated. After the SPO, a gallium oxynitride (GaON) dielectric layer was formed on the surface of p-GaN under the gate metal, and was studied by X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), high-resolution transmission electron microscopy (HR-TEM) and energy dispersion spectroscopy (EDS). In addition, the fabricated metal/GaON/p-GaN gate HEMT exhibited a large threshold voltage (VTH) improvement from 1.46 V to 2.47 V. Furthermore, the forward gate breakdown voltage (VGS,BD) increased from 7.55 V to 11.10 V, and the maximum forward gate operating voltage (VGS-max) significantly improved from 5.0 V to 7.80 V for a ten-year lifetime with a 63.2% failure rate. Kelvin Probe Force Microscopy (KPFM) reveals that the surface potential increased after SPO, and the shift of valence band maximum (VBM) obtained by XPS spectra was 0.7 eV lower than that of the p-GaN, which further improves the Schottky barrier height (SBH) at the gate metal/GaON interfaces to holes, thereby improving VTH and reducing IGS of the device. As a barrier layer, GaON suppressed the injection of carrier into the depletion region under a high electric field and enhanced the reliability of the gate.
在这封信中，通过使用选择性等离子氧化（SPO）和栅极金属蒸发前的额外低温退火步骤，证明了具有高阈值电压和更好栅极可靠性的 p-GaN 栅极高电子迁移率晶体管（HEMT）。在 SPO 之后，栅极金属下的 p-GaN 表面形成了氧化镓（GaON）介质层，并通过 X 射线光电子能谱（XPS）、二次离子质谱（SIMS）、高分辨率透射电子显微镜（HR-TEM）和能量色散光谱（EDS）进行了研究。此外，所制造的金属/GaON/p-GaN 栅极 HEMT 的阈值电压 (VTH) 从 1.46 V 大幅提高到 2.47 V。此外，正向栅极击穿电压（VGS,BD）从 7.55 V 提高到 11.10 V，最大正向栅极工作电压（VGS-max）从 5.0 V 显著提高到 7.80 V，使用寿命长达十年，故障率为 63.2%。开尔文探针力显微镜（KPFM）显示，SPO 后表面电位升高，XPS 光谱得到的价带最大值（VBM）偏移比 p-GaN 低 0.7 eV，这进一步提高了栅极金属/GaON 与空穴界面的肖特基势垒高度（SBH），从而提高了器件的 VTH，降低了 IGS。作为阻挡层，GaON 可抑制载流子在高电场下注入耗尽区，从而提高栅极的可靠性。
{"title":"Normally-off GaON/p-GaN gate HEMTs with using selective plasma oxidation: from structural characterization, performance improvement to physical mechanism","authors":"Nengtao Wu, Zhiheng Xing, L. Luo, Guoqiang Li","doi":"10.1088/1361-6641/ad3112","DOIUrl":"https://doi.org/10.1088/1361-6641/ad3112","url":null,"abstract":"\u0000 In this letter, a p-GaN gate high-electron-mobility transistor (HEMT) with a high threshold voltage and better gate reliability was demonstrated by using selective plasma oxidation (SPO) and an additional low-temperature annealing step before gate metal is evaporated. After the SPO, a gallium oxynitride (GaON) dielectric layer was formed on the surface of p-GaN under the gate metal, and was studied by X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), high-resolution transmission electron microscopy (HR-TEM) and energy dispersion spectroscopy (EDS). In addition, the fabricated metal/GaON/p-GaN gate HEMT exhibited a large threshold voltage (VTH) improvement from 1.46 V to 2.47 V. Furthermore, the forward gate breakdown voltage (VGS,BD) increased from 7.55 V to 11.10 V, and the maximum forward gate operating voltage (VGS-max) significantly improved from 5.0 V to 7.80 V for a ten-year lifetime with a 63.2% failure rate. Kelvin Probe Force Microscopy (KPFM) reveals that the surface potential increased after SPO, and the shift of valence band maximum (VBM) obtained by XPS spectra was 0.7 eV lower than that of the p-GaN, which further improves the Schottky barrier height (SBH) at the gate metal/GaON interfaces to holes, thereby improving VTH and reducing IGS of the device. As a barrier layer, GaON suppressed the injection of carrier into the depletion region under a high electric field and enhanced the reliability of the gate.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140258854","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":null,"pages":null},"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":null,"pages":null},"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}
In this study, we fabricated 76 × 127 µm2 green GaN-based micro-light-emitting-diodes (micro-LEDs) with atomic-layer-deposited (ALD) SiO2 passivation layers whose thicknesses were 0, 15, and 100 nm. The optoelectrical and communication performances of these devices were measured and analysed. The current-voltage results showed that ALD technology reduced the leakage current and enhanced the forward current of micro-LEDs. Compared with those of micro-LEDs without the passivation layer, the external quantum efficiency of micro-LEDs with 15 and 100 nm-thick SiO2 passivation layers increased by 23.64% and 19.47%, respectively. Furthermore, analysis of the EQE of the samples at room temperature using the ABC + f(n) model revealed the differences in the physical mechanisms of green micro-LEDs. Moreover, the communication performance indicated that ALD sidewall passivation reduced the carrier lifetime and improved the communication performance of green micro-LEDs.
在这项研究中，我们制作了 76 × 127 µm2 绿色氮化镓基微型发光二极管（micro-LED），其原子层沉积（ALD）二氧化硅钝化层的厚度分别为 0、15 和 100 nm。对这些器件的光电和通信性能进行了测量和分析。电流-电压结果表明，ALD 技术降低了微型 LED 的漏电流，提高了正向电流。与没有钝化层的微型 LED 相比，具有 15 nm 和 100 nm 厚 SiO2 钝化层的微型 LED 的外部量子效率分别提高了 23.64% 和 19.47%。此外，利用 ABC + f(n) 模型分析了样品在室温下的 EQE，揭示了绿色微型 LED 物理机制的差异。此外，通信性能表明，ALD 侧壁钝化降低了绿色微型 LED 的载流子寿命，提高了其通信性能。
{"title":"The impacts of SiO2 atomic-layer-deposited passivation layer thickness on GaN-based green micro-LEDs","authors":"Youcai Deng, Jinlan Chen, Saijun Li, He Huang, Zhong Liu, Zijun Yan, Shouqiang Lai, Lijie Zheng, Tianzhi Yang, Zhong Chen, Tingzhu Wu","doi":"10.1088/1361-6641/ad2b0a","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2b0a","url":null,"abstract":"In this study, we fabricated 76 × 127 <italic toggle=\"yes\">µ</italic>m<sup>2</sup> green GaN-based micro-light-emitting-diodes (micro-LEDs) with atomic-layer-deposited (ALD) SiO<sub>2</sub> passivation layers whose thicknesses were 0, 15, and 100 nm. The optoelectrical and communication performances of these devices were measured and analysed. The current-voltage results showed that ALD technology reduced the leakage current and enhanced the forward current of micro-LEDs. Compared with those of micro-LEDs without the passivation layer, the external quantum efficiency of micro-LEDs with 15 and 100 nm-thick SiO<sub>2</sub> passivation layers increased by 23.64% and 19.47%, respectively. Furthermore, analysis of the EQE of the samples at room temperature using the ABC + <italic toggle=\"yes\">f</italic>(n) model revealed the differences in the physical mechanisms of green micro-LEDs. Moreover, the communication performance indicated that ALD sidewall passivation reduced the carrier lifetime and improved the communication performance of green micro-LEDs.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140005779","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/ad2b09
I Blessing Meshach Dason, N Kasthuri, D Nirmal
Boltzmann limit is inevitable in conventional MOSFETs, which prevent them to be used for low-power applications. Research in device physics can address this problem by selection of proper materials satisfying our requirements. Recently, 2D transition metal di-chalcogenide (TMD) materials are gaining interest because they help alleviate short-channel effects and DIBL problems. The TMD materials are composed by covalently bonded weak van der Waals (vdW) interaction and can be realized as hetero structures with 2D ferro-electric material CuInP2S6 at the gate stack. This paper demonstrates a vdW negative capacitance field effect transistor (NCFET) structure in TCAD and the design was validated for voltage-current Characteristics. Parametric analysis shows MoS2 with phenomenal on/off ratio, narrow hysteresis than the counterparts. Simulation shows that MoS2 vdW NCFET has a high transconductance of 2.36 µS µm−1. A steep slope of 28.54 mV dec−1 is seen in MoS2 vdW NCFET which promises the performance of logic applications at a reduced supply voltage.
{"title":"TMD material investigation for a low hysteresis vdW NCFET logic transistor","authors":"I Blessing Meshach Dason, N Kasthuri, D Nirmal","doi":"10.1088/1361-6641/ad2b09","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2b09","url":null,"abstract":"Boltzmann limit is inevitable in conventional MOSFETs, which prevent them to be used for low-power applications. Research in device physics can address this problem by selection of proper materials satisfying our requirements. Recently, 2D transition metal di-chalcogenide (TMD) materials are gaining interest because they help alleviate short-channel effects and DIBL problems. The TMD materials are composed by covalently bonded weak van der Waals (vdW) interaction and can be realized as hetero structures with 2D ferro-electric material CuInP<sub>2</sub>S<sub>6</sub> at the gate stack. This paper demonstrates a vdW negative capacitance field effect transistor (NCFET) structure in TCAD and the design was validated for voltage-current Characteristics. Parametric analysis shows MoS<sub>2</sub> with phenomenal on/off ratio, narrow hysteresis than the counterparts. Simulation shows that MoS<sub>2</sub> vdW NCFET has a high transconductance of 2.36 <italic toggle=\"yes\">µ</italic>S <italic toggle=\"yes\">µ</italic>m<sup>−1</sup>. A steep slope of 28.54 mV dec<sup>−1</sup> is seen in MoS<sub>2</sub> vdW NCFET which promises the performance of logic applications at a reduced supply voltage.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140011074","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}
This work demonstrated a deep-ultraviolet (DUV) LED with an Al-graded p-AlGaN contact layer above the electron blocking layer to alleviate p-type contact resistance, the asymmetry of carriers transport, and the polarization effect. The fitting results from the ABC + f(n) model revealed that the LED has a higher radiative recombination coefficient than the conventional structures ever reported, which contributes to a lower carrier lifetime. The light output power of the LED at 350 mA is 44.71 mW, the peak external quantum efficiency (EQE) at 22.5 mA is 5.12%, the wall-plug efficiency at 9 mA is 4.40%. The 3 dB electrical-to-optical modulation bandwidth of the graded p-AlGaN contact layer LED is 390 MHz after impedance matching. In short, this study provides an in-depth analysis of the physical mechanism of the enhanced EQE and decreased carrier lifetime of DUV LEDs with Al-graded AlGaN as a p-type contact layer.
这项研究展示了一种深紫外（DUV）发光二极管，该发光二极管在电子阻挡层上方采用了铝级p-AlGaN接触层，以减轻p型接触电阻、载流子传输的不对称性和极化效应。ABC + f(n) 模型的拟合结果表明，该 LED 的辐射重组系数比以往报道的传统结构更高，从而导致载流子寿命更短。该 LED 在 350 mA 时的光输出功率为 44.71 mW，22.5 mA 时的峰值外部量子效率 (EQE) 为 5.12%，9 mA 时的壁插效率为 4.40%。阻抗匹配后，渐变 pAlGaN 接触层 LED 的 3 dB 电-光调制带宽为 390 MHz。总之，本研究深入分析了采用铝分级 AlGaN 作为 p 型接触层的 DUV LED 的 EQE 增强和载流子寿命降低的物理机制。
{"title":"Deep-ultraviolet LEDs with an Al-graded p-AlGaN layer exhibiting high wall-plug efficiency and high modulation bandwidth simultaneously","authors":"Bingyue Cui, Jie Yang, Xingfa Gao, Jiaheng He, Zhe Liu, Zhe Cheng, Yun Zhang","doi":"10.1088/1361-6641/ad238b","DOIUrl":"https://doi.org/10.1088/1361-6641/ad238b","url":null,"abstract":"This work demonstrated a deep-ultraviolet (DUV) LED with an Al-graded p-AlGaN contact layer above the electron blocking layer to alleviate p-type contact resistance, the asymmetry of carriers transport, and the polarization effect. The fitting results from the ABC + f(n) model revealed that the LED has a higher radiative recombination coefficient than the conventional structures ever reported, which contributes to a lower carrier lifetime. The light output power of the LED at 350 mA is 44.71 mW, the peak external quantum efficiency (EQE) at 22.5 mA is 5.12%, the wall-plug efficiency at 9 mA is 4.40%. The 3 dB electrical-to-optical modulation bandwidth of the graded p-AlGaN contact layer LED is 390 MHz after impedance matching. In short, this study provides an in-depth analysis of the physical mechanism of the enhanced EQE and decreased carrier lifetime of DUV LEDs with Al-graded AlGaN as a p-type contact layer.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140005448","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 : 2024-02-08DOI: 10.1088/1361-6641/ad2427
Zhengji Zhu, Chunshuang Chu, Kangkai Tian, Zhan Xuan, Zhiwei Xie, Ke Jiang, Yonghui Zhang, Xiaojuan Sun, Zi-Hui Zhang, Dabing Li
In this report, we propose a polarization-doped n-p-i-p-n GaN-based parallel phototransistor with thick GaN absorption layer. We employ an Al-composition-graded AlxGa1–xN layer for achieving p-type doping feature. We have studied the light propagation in the unintentionally doped GaN (i-GaN) absorption layer with different thicknesses, and the optimized thickness is 2 μm. As a result, the photo current of 10−2 A cm−2 and the responsivity of 2.12 A W−1 can be obtained at the applied bias of 5 V. In our fabricated device, during the current transport process, the photo-generated carriers are not along the device surface. Therefore, the photoconductive effect will be absent, and hence our device achieves a response speed with a rise time of 43.3 ms and a fall time of 86.4 ms.
{"title":"Polarization-doped n-p-i-p-n GaN-based parallel phototransistor with thick GaN absorption layer for achieving high responsivity","authors":"Zhengji Zhu, Chunshuang Chu, Kangkai Tian, Zhan Xuan, Zhiwei Xie, Ke Jiang, Yonghui Zhang, Xiaojuan Sun, Zi-Hui Zhang, Dabing Li","doi":"10.1088/1361-6641/ad2427","DOIUrl":"https://doi.org/10.1088/1361-6641/ad2427","url":null,"abstract":"In this report, we propose a polarization-doped n-p-i-p-n GaN-based parallel phototransistor with thick GaN absorption layer. We employ an Al-composition-graded Al<sub>x</sub>Ga<sub>1–x</sub>N layer for achieving p-type doping feature. We have studied the light propagation in the unintentionally doped GaN (i-GaN) absorption layer with different thicknesses, and the optimized thickness is 2 <italic toggle=\"yes\">μ</italic>m. As a result, the photo current of 10<sup>−2</sup> A cm<sup>−2</sup> and the responsivity of 2.12 A W<sup>−1</sup> can be obtained at the applied bias of 5 V. In our fabricated device, during the current transport process, the photo-generated carriers are not along the device surface. Therefore, the photoconductive effect will be absent, and hence our device achieves a response speed with a rise time of 43.3 ms and a fall time of 86.4 ms.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139753607","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}
The 2T1C pixel driver circuit for mini-LED direct display has been proposed, which separates the switching transistor and the driver transistor from the same display substrate, replaces the driver transistor with n-metal oxide semiconductor (NMOS), and combines printed circuit board substrate and thin-film transistor (TFT) substrate to improve the driving capability of the circuit. The NMOS was soldered with mini-LEDs simultaneously onto a substrate which connects to the a-Si TFT array. Two driving modes for a 32-level gray-scale display panel were investigated to compare the voltage-current and optical characteristics. The results demonstrated that the drain-driving mode is better suited for high brightness and high-power display application scenarios as it supports higher-driven currents, but the source-driving mode is more appropriate for precision gray-scale applications due to the higher current linearity of the mode.
提出了用于微型 LED 直接显示的 2T1C 像素驱动电路，该电路将开关晶体管和驱动晶体管从同一个显示基板上分离出来，用正金属氧化物半导体（NMOS）取代驱动晶体管，并将印刷电路板基板和薄膜晶体管（TFT）基板结合起来，以提高电路的驱动能力。NMOS 与微型 LED 同时焊接在连接到非晶硅 TFT 阵列的基板上。研究了 32 级灰度显示面板的两种驱动模式，以比较电压-电流和光学特性。结果表明，漏极驱动模式更适合高亮度和高功率显示应用场景，因为它支持更高的驱动电流，但源极驱动模式更适合精密灰度应用，因为该模式的电流线性度更高。
{"title":"Integrated 2T1C pixel circuit with a-Si TFT and NMOS for active matrix mini-LED displays","authors":"Chenming Zhong, Guangyao Li, Xi Zheng, Lihong Zhu, Jianbang Zhuang, Yijun Lu, Zhong Chen, Weijie Guo","doi":"10.1088/1361-6641/ad238c","DOIUrl":"https://doi.org/10.1088/1361-6641/ad238c","url":null,"abstract":"The 2T1C pixel driver circuit for mini-LED direct display has been proposed, which separates the switching transistor and the driver transistor from the same display substrate, replaces the driver transistor with n-metal oxide semiconductor (NMOS), and combines printed circuit board substrate and thin-film transistor (TFT) substrate to improve the driving capability of the circuit. The NMOS was soldered with mini-LEDs simultaneously onto a substrate which connects to the a-Si TFT array. Two driving modes for a 32-level gray-scale display panel were investigated to compare the voltage-current and optical characteristics. The results demonstrated that the drain-driving mode is better suited for high brightness and high-power display application scenarios as it supports higher-driven currents, but the source-driving mode is more appropriate for precision gray-scale applications due to the higher current linearity of the mode.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139753555","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 : 2024-01-26DOI: 10.1088/1361-6641/ad22fd
Yuhai Yuan, Yanfeng Jiang
Magnetic tunnel junctions (MTJs), as the core storage unit of magneto resistive random-access memory (MRAM), have received a lot of attention and have a very important position in spintronics. In the MTJ devices, magnetic/nonmagnetic heterojunction structures are included, consisting of magnetic metals and magnetic insulators or nonmagnetic metals. The interface of the heterojunction has certain physical effects that can affect the performance of MTJ devices. In the review, combined with the existing research results, the physical mechanism of magnetic/non-magnetic heterojunction interface coupling is discussed. The influence of the interface effect of the heterojunction on the performance of MTJ devices is studied, and the optimization method is proposed specifically. This work systematically summarizes the interface effect of magnetic/non-magnetic heterojunction.
{"title":"Review on magnetic/nonmagnetic heterojunction interface effects on spintronic MTJ devices","authors":"Yuhai Yuan, Yanfeng Jiang","doi":"10.1088/1361-6641/ad22fd","DOIUrl":"https://doi.org/10.1088/1361-6641/ad22fd","url":null,"abstract":"\u0000 Magnetic tunnel junctions (MTJs), as the core storage unit of magneto resistive random-access memory (MRAM), have received a lot of attention and have a very important position in spintronics. In the MTJ devices, magnetic/nonmagnetic heterojunction structures are included, consisting of magnetic metals and magnetic insulators or nonmagnetic metals. The interface of the heterojunction has certain physical effects that can affect the performance of MTJ devices. In the review, combined with the existing research results, the physical mechanism of magnetic/non-magnetic heterojunction interface coupling is discussed. The influence of the interface effect of the heterojunction on the performance of MTJ devices is studied, and the optimization method is proposed specifically. This work systematically summarizes the interface effect of magnetic/non-magnetic heterojunction.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139594134","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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