Pub Date : 2024-07-11DOI: 10.1088/1361-6641/ad5e17
Yibo Hu, Zhipeng Ren, Yizhe Yin and Jing Chen
In this work, we systematically investigate the DC performance of fully depleted silicon-on-insulator (FD-SOI) MOSFETs at both room and cryogenic temperatures as low as 77 K. The influences of back-gate bias on normal and flip-well devices are measured and analyzed. Both types devices display non-linear behaviors when adjusting the back-gate voltage at cryogenic temperatures. Notably, the non-linear effects are more prominent in normal-well devices. The possible reasons are analyzed and verified by technology computer aided design simulation, suggesting that normal-well devices are more susceptible to the formation of depletion regions between the buried oxide layer and the well. This phenomenon disrupts the linearity of the back-gate effect. This research contributes to understanding and characterizing of the back-gate effects in cryogenic environments and holds potential for high-performance computing applications.
在这项工作中，我们系统地研究了全耗尽型硅绝缘体（FD-SOI）MOSFET 在室温和低至 77 K 的低温条件下的直流性能。在低温条件下调节后栅极电压时，这两种器件都显示出非线性行为。值得注意的是，非线性效应在正常阱器件中更为突出。通过计算机辅助设计模拟技术分析和验证了可能的原因，认为正常阱器件更容易在埋入氧化层和阱之间形成耗尽区。这种现象破坏了背栅效应的线性。这项研究有助于理解和描述低温环境中的背栅效应，并为高性能计算应用提供了潜力。
{"title":"Nonlinear behaviors in back-gate effects of FDSOI MOSFETs at cryogenic temperatures","authors":"Yibo Hu, Zhipeng Ren, Yizhe Yin and Jing Chen","doi":"10.1088/1361-6641/ad5e17","DOIUrl":"https://doi.org/10.1088/1361-6641/ad5e17","url":null,"abstract":"In this work, we systematically investigate the DC performance of fully depleted silicon-on-insulator (FD-SOI) MOSFETs at both room and cryogenic temperatures as low as 77 K. The influences of back-gate bias on normal and flip-well devices are measured and analyzed. Both types devices display non-linear behaviors when adjusting the back-gate voltage at cryogenic temperatures. Notably, the non-linear effects are more prominent in normal-well devices. The possible reasons are analyzed and verified by technology computer aided design simulation, suggesting that normal-well devices are more susceptible to the formation of depletion regions between the buried oxide layer and the well. This phenomenon disrupts the linearity of the back-gate effect. This research contributes to understanding and characterizing of the back-gate effects in cryogenic environments and holds potential for high-performance computing applications.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141610266","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 : 2024-07-03DOI: 10.1088/1361-6641/ad5b80
Junji Cheng, Queyang Wang, Yikai Liu, Guo Ding, Minming Zhang, Bo Yi, Haimeng Huang and Hongqiang Yang
A novel structure of p-GaN high-electron-mobility transistor (HEMT) is proposed and studied. It features two composite layers. One is the composite passivation (CP) layer consisting of Si3N4 and high-permittivity (HK) film. The other is a composite barrier (CB) layer consisting of AlxGa1−xN/AlN/Al0.23Ga0.77N. Due to the coordinated effect of CP and CB, the specific on-resistance (RON, SP) can be reduced under the premise of ensuring breakdown voltage (BV). Meanwhile, since the HK film in CP introduces a mechanism to automatically compensate the hot electrons trapped by surface states, the current collapse effect could be suppressed. According to the simulation results, in comparison with the conventional p-GaN HEMT, the proposed one using TiO2 as the HK material and using Al-component of 0.35 for AlxGa1−xN gains a 29.5% reduction in RON, SP while getting a 9.8% increase in BV, which contributes to a 50.5% decrease in the energy loss during one cycle at 200 kHz. It is also demonstrated by the simulation results that the current collapse in the proposed device is reduced by 28.6%. Thereby, a promising p-GaN HEMT with improved performance and reliability is invented.
{"title":"Study on a p-GaN HEMT with composite passivation and composite barrier layers","authors":"Junji Cheng, Queyang Wang, Yikai Liu, Guo Ding, Minming Zhang, Bo Yi, Haimeng Huang and Hongqiang Yang","doi":"10.1088/1361-6641/ad5b80","DOIUrl":"https://doi.org/10.1088/1361-6641/ad5b80","url":null,"abstract":"A novel structure of p-GaN high-electron-mobility transistor (HEMT) is proposed and studied. It features two composite layers. One is the composite passivation (CP) layer consisting of Si3N4 and high-permittivity (HK) film. The other is a composite barrier (CB) layer consisting of AlxGa1−xN/AlN/Al0.23Ga0.77N. Due to the coordinated effect of CP and CB, the specific on-resistance (RON, SP) can be reduced under the premise of ensuring breakdown voltage (BV). Meanwhile, since the HK film in CP introduces a mechanism to automatically compensate the hot electrons trapped by surface states, the current collapse effect could be suppressed. According to the simulation results, in comparison with the conventional p-GaN HEMT, the proposed one using TiO2 as the HK material and using Al-component of 0.35 for AlxGa1−xN gains a 29.5% reduction in RON, SP while getting a 9.8% increase in BV, which contributes to a 50.5% decrease in the energy loss during one cycle at 200 kHz. It is also demonstrated by the simulation results that the current collapse in the proposed device is reduced by 28.6%. Thereby, a promising p-GaN HEMT with improved performance and reliability is invented.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551898","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 : 2024-07-02DOI: 10.1088/1361-6641/ad59bc
Paiwen Fang, Zhengyi Liao, Danni Su, Jun Liang, Xinzhong Wang and Yanli Pei
A suitable semiconductor surface treatment could improve the gate dielectric quality and reduce the interface states and traps to enhance the performance of metal–oxide semiconductor capacitors (MOSCAPs). In this paper, β-Ga2O3 surface treatment using NaOH solution prior to atomic layer deposition of Al2O3 was investigated. In comparison with piranha pretreatment, MOSCAPs with NaOH solution surface pretreatment show a larger maximum accumulation capacitance with less frequency dispersion, reduced charges/traps and interface state density Dit. The improvement in MOSCAPs performance could be attributed to the NaOH solution pretreatment induced slight surface etching effect and relatively effective hydroxylation surface. These results suggest that the process optimization of NaOH solution surface pretreatment could lead to further improvement of β-Ga2O3 MOSCAPs and have a potential in application of β-Ga2O3 metal–oxide semiconductor field-effect transistors in the future.
{"title":"Impact of NaOH solution surface treatment on Al2O3/β-Ga2O3 MOS capacitors","authors":"Paiwen Fang, Zhengyi Liao, Danni Su, Jun Liang, Xinzhong Wang and Yanli Pei","doi":"10.1088/1361-6641/ad59bc","DOIUrl":"https://doi.org/10.1088/1361-6641/ad59bc","url":null,"abstract":"A suitable semiconductor surface treatment could improve the gate dielectric quality and reduce the interface states and traps to enhance the performance of metal–oxide semiconductor capacitors (MOSCAPs). In this paper, β-Ga2O3 surface treatment using NaOH solution prior to atomic layer deposition of Al2O3 was investigated. In comparison with piranha pretreatment, MOSCAPs with NaOH solution surface pretreatment show a larger maximum accumulation capacitance with less frequency dispersion, reduced charges/traps and interface state density Dit. The improvement in MOSCAPs performance could be attributed to the NaOH solution pretreatment induced slight surface etching effect and relatively effective hydroxylation surface. These results suggest that the process optimization of NaOH solution surface pretreatment could lead to further improvement of β-Ga2O3 MOSCAPs and have a potential in application of β-Ga2O3 metal–oxide semiconductor field-effect transistors in the future.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141530938","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 : 2024-06-23DOI: 10.1088/1361-6641/ad575b
Yihong Ji, Martin Frentrup, Simon M Fairclough, Yingjun Liu, Tongtong Zhu and Rachel A Oliver
In this study, possible origins of small V-pits observed in multiple quantum wells (MQWs) overgrown on as-grown and porosified InGaN superlattice (SL) pseudo-substrates have been investigated. Various cross-sectional transmission microscopy techniques revealed that some of the small V-pits arise from the intersection of threading defects with the sample surface, either as part of dislocation loops or trench defects. Some small V-pits without threading defects are also observed. Energy dispersive x-ray study indicates that the Indium content in the MQWs increases with the averaged porosity of the underlying template, which may either be attributed to a reduced compositional pulling effect or the low thermal conductivity of the porous layer. Furthermore, the porous structure inhibits the glide or extension of the misfit dislocations (MD) within the InGaN SL. The extra strain induced by the higher Indium content and the hindered movement of the MDs combined may explain the observed additional small V-pits present on the MQWs overgrown on the more relaxed templates.
在这项研究中，我们研究了在原生和多孔化 InGaN 超晶格（SL）伪基底上叠加生长的多量子阱（MQW）中观察到的小 V 形坑的可能来源。各种横截面透射显微镜技术显示，一些小 V 形坑是由穿线缺陷与样品表面的交汇处产生的，这些穿线缺陷或是位错环的一部分，或是沟槽缺陷的一部分。此外，还观察到一些没有穿线缺陷的小 V 形凹坑。能量色散 X 射线研究表明，MQW 中的铟含量随着底层模板的平均孔隙率增加而增加，这可能是由于成分拉动效应减弱或多孔层的热传导率较低。此外，多孔结构抑制了 InGaN SL 内错位（MD）的滑行或延伸。铟含量较高引起的额外应变和 MD 运动受阻共同作用，可能解释了为什么在较宽松模板上生长的 MQW 上会出现额外的小 V 形凹坑。
{"title":"Microscopy studies of InGaN MQWs overgrown on porosified InGaN superlattice pseudo-substrates","authors":"Yihong Ji, Martin Frentrup, Simon M Fairclough, Yingjun Liu, Tongtong Zhu and Rachel A Oliver","doi":"10.1088/1361-6641/ad575b","DOIUrl":"https://doi.org/10.1088/1361-6641/ad575b","url":null,"abstract":"In this study, possible origins of small V-pits observed in multiple quantum wells (MQWs) overgrown on as-grown and porosified InGaN superlattice (SL) pseudo-substrates have been investigated. Various cross-sectional transmission microscopy techniques revealed that some of the small V-pits arise from the intersection of threading defects with the sample surface, either as part of dislocation loops or trench defects. Some small V-pits without threading defects are also observed. Energy dispersive x-ray study indicates that the Indium content in the MQWs increases with the averaged porosity of the underlying template, which may either be attributed to a reduced compositional pulling effect or the low thermal conductivity of the porous layer. Furthermore, the porous structure inhibits the glide or extension of the misfit dislocations (MD) within the InGaN SL. The extra strain induced by the higher Indium content and the hindered movement of the MDs combined may explain the observed additional small V-pits present on the MQWs overgrown on the more relaxed templates.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141500860","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 : 2024-06-19DOI: 10.1088/1361-6641/ad5100
Jiaxin Zhang, Liqiong Deng, Shihong Xia, Chenyu Guo, Kunzi Liu, Li Chen, Wei Liu, Hui Xiao, Zhenhai Yang, Wei Guo and Jichun Ye
Solid-state ultraviolet (UV) photodetectors (PDs) have received significant attention due to their advantages of small size, absence of external cooling, high selectivity and the ability to utilize the energy band structure semiconductor materials to achieve detection across various wavelengths. III-nitride thin films, as typical wide bandgap semiconductors with mature n-type and p-type doping capabilities, are ideal candidates for solid-state UV-PDs. However, a combination of III-nitride and other wide bandgap materials can either enrich the functionality of devices such as spectrum-selective and broadband UV detectionor offer opportunities to enhance device performance, including high photoresponsivity, high external quantum efficiency, low dark current and fast response time. This topical review focuses on giving a thorough review of the III-nitride-based hybrid-type UV PDs, their recent progress and future prospects. We highlight the different optical and electrical properties of various materials including GaN, Ga2O3, ZnO, perovskite, etc. By carefully choosing the materials on both sides of the heterojunction and modulating the thickness and Fermi levels and corresponding layers, p–i–n, Schottky or metal–semiconductor–metal-type PDs were successfully fabricated. They displayed outstanding device performance and novel spectral-selective properties. The advantages for future development of these hybrid-type PDs will be discussed, such as inherently formed p–n junction with large depletion regions at the interface of two different materials and capability of bandgap engineering to tune the band offset between the conduction and valence bands, thus enabling large barrier height for one type of carrier without influencing the other. The drawbacks of hybrid-type UV-PD due to poor interface quality and challenges in forming electrical contact in nanostructured hybrid UV-PD will also be discussed.
固态紫外线（UV）光电探测器（PD）具有体积小、无需外部冷却、选择性高以及能够利用半导体材料的能带结构实现各种波长的检测等优点，因此受到了广泛关注。III 族氮化物薄膜是典型的宽带隙半导体，具有成熟的 n 型和 p 型掺杂能力，是固态紫外-光致发光器件的理想候选材料。然而，III 族氮化物与其他宽带隙材料的结合既可以丰富器件的功能，如光谱选择性和宽带紫外检测，也可以提供提高器件性能的机会，包括高光致发光性、高外部量子效率、低暗电流和快速响应时间。本专题综述将重点全面回顾基于 III 族氮化物的混合型紫外光直放电器件及其最新进展和未来前景。我们重点介绍了各种材料（包括氮化镓、氧化镓、氧化锌、过氧化物等）的不同光学和电学特性。通过精心选择异质结两侧的材料、调节厚度和费米级以及相应的层，成功制备出了 p-i-n、肖特基或金属-半导体-金属型 PD。它们显示出出色的器件性能和新颖的光谱选择特性。我们将讨论这些混合型光致发光器件未来发展的优势，例如在两种不同材料的界面上固有地形成了具有较大耗尽区的 p-n 结，以及通过带隙工程来调整导带和价带之间的带偏移，从而使一种载流子具有较大的势垒高度而不影响另一种载流子的能力。此外，还将讨论混合型 UV-PD 因界面质量差而产生的缺点，以及在纳米结构混合 UV-PD 中形成电接触所面临的挑战。
{"title":"Recent advances and prospects for a GaN-based hybrid type ultraviolet photodetector","authors":"Jiaxin Zhang, Liqiong Deng, Shihong Xia, Chenyu Guo, Kunzi Liu, Li Chen, Wei Liu, Hui Xiao, Zhenhai Yang, Wei Guo and Jichun Ye","doi":"10.1088/1361-6641/ad5100","DOIUrl":"https://doi.org/10.1088/1361-6641/ad5100","url":null,"abstract":"Solid-state ultraviolet (UV) photodetectors (PDs) have received significant attention due to their advantages of small size, absence of external cooling, high selectivity and the ability to utilize the energy band structure semiconductor materials to achieve detection across various wavelengths. III-nitride thin films, as typical wide bandgap semiconductors with mature n-type and p-type doping capabilities, are ideal candidates for solid-state UV-PDs. However, a combination of III-nitride and other wide bandgap materials can either enrich the functionality of devices such as spectrum-selective and broadband UV detectionor offer opportunities to enhance device performance, including high photoresponsivity, high external quantum efficiency, low dark current and fast response time. This topical review focuses on giving a thorough review of the III-nitride-based hybrid-type UV PDs, their recent progress and future prospects. We highlight the different optical and electrical properties of various materials including GaN, Ga2O3, ZnO, perovskite, etc. By carefully choosing the materials on both sides of the heterojunction and modulating the thickness and Fermi levels and corresponding layers, p–i–n, Schottky or metal–semiconductor–metal-type PDs were successfully fabricated. They displayed outstanding device performance and novel spectral-selective properties. The advantages for future development of these hybrid-type PDs will be discussed, such as inherently formed p–n junction with large depletion regions at the interface of two different materials and capability of bandgap engineering to tune the band offset between the conduction and valence bands, thus enabling large barrier height for one type of carrier without influencing the other. The drawbacks of hybrid-type UV-PD due to poor interface quality and challenges in forming electrical contact in nanostructured hybrid UV-PD will also be discussed.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141500912","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 : 2024-06-17DOI: 10.1088/1361-6641/ad5041
Arghyadeep Sarkar
In this study, we examined the gate leakage characteristics of normally off pGaN/AlGaN/GaN HEMTs through a simulation study. The Fowler Nordheim Tunneling (FNT) mechanism mainly contributes to the gate leakage process as indicated by the Technology Computer-Aided Design (TCAD) simulation. However, at low bias, the FNT undercalculates the leakage current since the electric field is low in this region. This extra leakage current component at this low bias region can be attributed to the presence of surface traps. Trap-assisted tunneling current along with the FNT current can explain forward leakage characteristics of the pGaN HEMTs. Our TCAD simulations were matched with the experimental data for five devices from four different research groups to support this claim. Using TCAD simulations, we have been able to analyze several device parameters including the various potential drops inside the gate stack structure. We were able to identify some of the trap levels and compare them to the dominant defects expected to be present in the pGaN cap layer. Furthermore, we studied the effects of different device parameters on the gate leakage process in the pGaN HEMT.
{"title":"Investigation of the forward gate leakage current in pGaN/AlGaN/GaN HEMTs through TCAD simulations","authors":"Arghyadeep Sarkar","doi":"10.1088/1361-6641/ad5041","DOIUrl":"https://doi.org/10.1088/1361-6641/ad5041","url":null,"abstract":"In this study, we examined the gate leakage characteristics of normally off pGaN/AlGaN/GaN HEMTs through a simulation study. The Fowler Nordheim Tunneling (FNT) mechanism mainly contributes to the gate leakage process as indicated by the Technology Computer-Aided Design (TCAD) simulation. However, at low bias, the FNT undercalculates the leakage current since the electric field is low in this region. This extra leakage current component at this low bias region can be attributed to the presence of surface traps. Trap-assisted tunneling current along with the FNT current can explain forward leakage characteristics of the pGaN HEMTs. Our TCAD simulations were matched with the experimental data for five devices from four different research groups to support this claim. Using TCAD simulations, we have been able to analyze several device parameters including the various potential drops inside the gate stack structure. We were able to identify some of the trap levels and compare them to the dominant defects expected to be present in the pGaN cap layer. Furthermore, we studied the effects of different device parameters on the gate leakage process in the pGaN HEMT.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141500913","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 : 2024-06-13DOI: 10.1088/1361-6641/ad57e6
Le Trung Hieu, S. Rathaur, Chee-How Lu, You-Chen Weng, Yuan Lin, Chun-Hsiung Lin, Quark Yungsung Chen, Edward Yi Chang
In this study, the growth of a high-quality AlGaN/GaN high electron mobility transistor (HEMT) heterostructure on silicon (Si) by metal-organic chemical vapor deposition (MOCVD) was investigated by utilizing the both AlN/GaN superlattice (SL) and Al0.07Ga0.93N back barrier (BB) techniques. Atomic force microscope (AFM) and high-resolution x-ray diffractometer (HR-XRD) confirm low surface roughness of 0.26 – 0.34 nm and the formation of high-quality AlN/GaN SL and GaN channel. The AlGaN/GaN heterostructures exhibit high electron mobility of up to 1700 cm2/V∙s and high carrier concentration density of (1.02 – 1.06 × 1013 cm-2) for both heterostructures. The AlGaN/GaN HEMT devices demonstrate low specific contact resistivity (c) of 2.7 × 10-6 Ω·cm2 and low contact resistance (RC) of 0.3 Ω·mm for the heterostructure with BB layer. Furthermore, the DC characteristics demonstrate that incorporating Al0.07Ga0.93N BB in the heterostructure results in a 19.2% increase in lateral breakdown voltage (with a 10 µm spacing) and a 27.5% increase in vertical breakdown voltage (at 1 mA/cm2), compared to the heterostructure without Al0.07Ga0.93N BB within the AlN/GaN SL structure. Moreover, improvement of 10.6% in maximum saturation current (IDS) and 15.2% in on-resistance (RON)has been for the device fabricated on Al0.07Ga0.93N BB structure. The insertion loss of the buffer layer improves to –1.40 dB/mm at 40 GHz. Consequently, the proposed heterostructure investigated in this study demonstrates suitability for electronic device applications.
{"title":"Low contact resistance and high breakdown voltage of AlGaN/GaN HEMT grown on silicon using both AlN/GaN superlattice and Al0.07Ga0.93N back barrier layer","authors":"Le Trung Hieu, S. Rathaur, Chee-How Lu, You-Chen Weng, Yuan Lin, Chun-Hsiung Lin, Quark Yungsung Chen, Edward Yi Chang","doi":"10.1088/1361-6641/ad57e6","DOIUrl":"https://doi.org/10.1088/1361-6641/ad57e6","url":null,"abstract":"\u0000 In this study, the growth of a high-quality AlGaN/GaN high electron mobility transistor (HEMT) heterostructure on silicon (Si) by metal-organic chemical vapor deposition (MOCVD) was investigated by utilizing the both AlN/GaN superlattice (SL) and Al0.07Ga0.93N back barrier (BB) techniques. Atomic force microscope (AFM) and high-resolution x-ray diffractometer (HR-XRD) confirm low surface roughness of 0.26 – 0.34 nm and the formation of high-quality AlN/GaN SL and GaN channel. The AlGaN/GaN heterostructures exhibit high electron mobility of up to 1700 cm2/V∙s and high carrier concentration density of (1.02 – 1.06 × 1013 cm-2) for both heterostructures. The AlGaN/GaN HEMT devices demonstrate low specific contact resistivity (c) of 2.7 × 10-6 Ω·cm2 and low contact resistance (RC) of 0.3 Ω·mm for the heterostructure with BB layer. Furthermore, the DC characteristics demonstrate that incorporating Al0.07Ga0.93N BB in the heterostructure results in a 19.2% increase in lateral breakdown voltage (with a 10 µm spacing) and a 27.5% increase in vertical breakdown voltage (at 1 mA/cm2), compared to the heterostructure without Al0.07Ga0.93N BB within the AlN/GaN SL structure. Moreover, improvement of 10.6% in maximum saturation current (IDS) and 15.2% in on-resistance (RON)has been for the device fabricated on Al0.07Ga0.93N BB structure. The insertion loss of the buffer layer improves to –1.40 dB/mm at 40 GHz. Consequently, the proposed heterostructure investigated in this study demonstrates suitability for electronic device applications.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141345983","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 : 2024-06-12DOI: 10.1088/1361-6641/ad5467
T Srinivasa Reddy, S Vijaya Krishna, A Vinaya Kumar, M Ramanjaneyulu, N Raja Sekhar and M C Santhosh Kumar
In this study, aluminum doped lead sulfide (PbS:Al) thin films were deposited on soda lime glass substrates using chemical bath deposition (CBD) technique. The structural, morphological, optical and electrical properties of as-deposited PbS thin films were studied as a function of Al concentration (0, 2, 4, 6, 8 at. %). The deposited films can be analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), UV-Vis-NIR spectroscopy and Hall measurement. From SEM, it was evident that the thickness of the films decreased from 750 nm (0 at. %) to 280 nm (8 at. %) with increased Al concentration. XRD analysis revealed that the prepared films exhibited face centered cubic structure without any other binary phases. The average crystallite size of the films decreased from 33.71 to 20.45 nm. The direct optical band gap values were increased from 0.90 to 1.29 eV. The optical parameters such as refractive index (n), extinction coefficient (k), real (ɛ1) and imaginary (ɛ2) parts of the dielectric constant were 1.51–2.04, 0.0035–0.0075, 2.50–6.20 and 0.005–0.16 respectively. The absorption coefficient (α) of all the deposited films was in the range of ≈105 cm−1. The electrical resistivity of the deposited films was found in the range of 102–103 Ω·cm. The overall analysis indicate that the deposited PbS:Al thin film shows promise as an absorbing layer for heterojunction solar cell devices.
{"title":"Facile synthesis and characterization of PbS thin films doped with various aluminum concentrations for photovoltaic applications","authors":"T Srinivasa Reddy, S Vijaya Krishna, A Vinaya Kumar, M Ramanjaneyulu, N Raja Sekhar and M C Santhosh Kumar","doi":"10.1088/1361-6641/ad5467","DOIUrl":"https://doi.org/10.1088/1361-6641/ad5467","url":null,"abstract":"In this study, aluminum doped lead sulfide (PbS:Al) thin films were deposited on soda lime glass substrates using chemical bath deposition (CBD) technique. The structural, morphological, optical and electrical properties of as-deposited PbS thin films were studied as a function of Al concentration (0, 2, 4, 6, 8 at. %). The deposited films can be analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), UV-Vis-NIR spectroscopy and Hall measurement. From SEM, it was evident that the thickness of the films decreased from 750 nm (0 at. %) to 280 nm (8 at. %) with increased Al concentration. XRD analysis revealed that the prepared films exhibited face centered cubic structure without any other binary phases. The average crystallite size of the films decreased from 33.71 to 20.45 nm. The direct optical band gap values were increased from 0.90 to 1.29 eV. The optical parameters such as refractive index (n), extinction coefficient (k), real (ɛ1) and imaginary (ɛ2) parts of the dielectric constant were 1.51–2.04, 0.0035–0.0075, 2.50–6.20 and 0.005–0.16 respectively. The absorption coefficient (α) of all the deposited films was in the range of ≈105 cm−1. The electrical resistivity of the deposited films was found in the range of 102–103 Ω·cm. The overall analysis indicate that the deposited PbS:Al thin film shows promise as an absorbing layer for heterojunction solar cell devices.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141530939","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 : 2024-06-07DOI: 10.1088/1361-6641/ad5581
Yuheng Zhang, Jing Yang, F. Liang, Zongshun Liu, Yufei Hou, Bing Liu, Fu Zheng, Xuefeng Liu, Degang Zhao
The relationship between stress and dislocation density in MOCVD epitaxial AlN was studied. It has been found that the aluminum nitride (AlN) epitaxial layer generates tensile stress when the crystal islands are merged. By controlling the size and density of crystal islands at the end of 3D growth, the tensile stress generated during epitaxy can be effectively reduced. Mechanical calculations show that there is a linear relationship between the edge thread dislocations density of AlN and the tensile stress during growth. By controlling the stress during AlN growth below 0.1 Gpa, a high-quality AlN sample with an edge thread dislocation density of 6.31 × 107 cm−2 was obtained.
{"title":"Effect of stress control by growth adjustment on the edge thread dislocation density of AlN grown on the sapphire","authors":"Yuheng Zhang, Jing Yang, F. Liang, Zongshun Liu, Yufei Hou, Bing Liu, Fu Zheng, Xuefeng Liu, Degang Zhao","doi":"10.1088/1361-6641/ad5581","DOIUrl":"https://doi.org/10.1088/1361-6641/ad5581","url":null,"abstract":"The relationship between stress and dislocation density in MOCVD epitaxial AlN was studied. It has been found that the aluminum nitride (AlN) epitaxial layer generates tensile stress when the crystal islands are merged. By controlling the size and density of crystal islands at the end of 3D growth, the tensile stress generated during epitaxy can be effectively reduced. Mechanical calculations show that there is a linear relationship between the edge thread dislocations density of AlN and the tensile stress during growth. By controlling the stress during AlN growth below 0.1 Gpa, a high-quality AlN sample with an edge thread dislocation density of 6.31 × 107 cm−2 was obtained.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141373032","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 : 2024-06-07DOI: 10.1088/1361-6641/ad5582
Arun Nagendra, J. Trombley, E. H. Chan
To predict possible minority-carrier effects in multi-level phase change memory devices, minority-carrier transport through an isotype amorphous-crystalline Ge2Sb2Te5 heterojunction under forward bias is studied for the first time. Electron thermionic emission, thermal generation, drift, diffusion, radiative recombination, Auger recombination, Schockley-Read-Hall recombination via conduction band tails, valence band tails, acceptor-type mid-gap, donor-type mid-gap and multivalent defect distributions, as well as surface recombination are considered in the construction of the steady-state Continuity Equation relevant to the representative a-GST/c-GST heterojunction, which is then numerically solved at 0.15 V and 0.40 V using solar cell capacitance simulations. Provided that radiative recombination is negligible and defect distributions within the band gap of either layer are energetically localised, the simulated electron concentration, electron current density and electron quasi-Fermi level distributions across the heterojunction reveal that transport through the amorphous layer limits electron flow through the device. At low applied bias, net recombination and diffusion within the quasi-neutral region of the amorphous layer dominate, whereas at larger applied bias, drift across the quasi-neutral region, due to the electric field induced by the significant majority-carrier current density, as well as surface recombination at the amorphous layer contact contribute significantly. Within the crystalline layer, net generation of electrons supplies the amorphous layer at all biases, assuming that the crystalline layer contact does not limit electron transport. Thus, the effect of forward bias on the dominant transport mechanisms through the a-GST/c-GST heterojunction demonstrated herein represents the key contribution of this paper.
为了预测多电平相变存储器件中可能出现的少数载流子效应，我们首次研究了在正向偏压条件下，少数载流子通过同型非晶-晶体 Ge2Sb2Te5 异质结的传输。在构建与具有代表性的 a-GST/c-GST 异质结相关的稳态连续性方程时，考虑了电子热离子发射、热生成、漂移、扩散、辐射重组、奥格重组、通过导带尾、价带尾、受体型中隙、供体型中隙和多价缺陷分布的 Schockley-Read-Hall 重组，以及表面重组。15 V 和 0.40 V 时的数值求解。如果辐射重组可以忽略不计，并且任一层带隙内的缺陷分布都是能量局域化的，那么异质结上的模拟电子浓度、电子电流密度和电子准费米级分布都表明，通过非晶层的传输限制了电子在器件中的流动。在较低的外加偏压下，非晶层准中性区域内的净重组和扩散占主导地位，而在较大的外加偏压下，由于显著的多数载流子电流密度所引起的电场导致的准中性区域漂移以及非晶层接触处的表面重组则起着重要作用。在晶体层内，假设晶体层接触面不限制电子传输，那么在所有偏压条件下，电子的净产生都会为非晶层提供能量。因此，本文展示的正向偏压对通过 a-GST/c-GST 异质结的主要传输机制的影响是本文的主要贡献。
{"title":"Minority-carrier transport through an isotype amorphous-crystalline Ge2Sb2Te5 heterojunction under forward bias","authors":"Arun Nagendra, J. Trombley, E. H. Chan","doi":"10.1088/1361-6641/ad5582","DOIUrl":"https://doi.org/10.1088/1361-6641/ad5582","url":null,"abstract":"\u0000 To predict possible minority-carrier effects in multi-level phase change memory devices, minority-carrier transport through an isotype amorphous-crystalline Ge2Sb2Te5 heterojunction under forward bias is studied for the first time. Electron thermionic emission, thermal generation, drift, diffusion, radiative recombination, Auger recombination, Schockley-Read-Hall recombination via conduction band tails, valence band tails, acceptor-type mid-gap, donor-type mid-gap and multivalent defect distributions, as well as surface recombination are considered in the construction of the steady-state Continuity Equation relevant to the representative a-GST/c-GST heterojunction, which is then numerically solved at 0.15 V and 0.40 V using solar cell capacitance simulations. Provided that radiative recombination is negligible and defect distributions within the band gap of either layer are energetically localised, the simulated electron concentration, electron current density and electron quasi-Fermi level distributions across the heterojunction reveal that transport through the amorphous layer limits electron flow through the device. At low applied bias, net recombination and diffusion within the quasi-neutral region of the amorphous layer dominate, whereas at larger applied bias, drift across the quasi-neutral region, due to the electric field induced by the significant majority-carrier current density, as well as surface recombination at the amorphous layer contact contribute significantly. Within the crystalline layer, net generation of electrons supplies the amorphous layer at all biases, assuming that the crystalline layer contact does not limit electron transport. Thus, the effect of forward bias on the dominant transport mechanisms through the a-GST/c-GST heterojunction demonstrated herein represents the key contribution of this paper.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141372743","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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