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":"50 1","pages":""},"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":"18 1","pages":""},"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":"8 1","pages":""},"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":"12 1","pages":""},"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":"3 1","pages":""},"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 : 2024-06-12DOI: 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":"19 1","pages":""},"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 : 2024-05-28DOI: 10.1088/1361-6641/ad4d5b
Yazhou Li, Weizhen Yao, Zhanhong Ma, Shaoyan Yang, Xianglin Liu, Chengming Li and Zhanguo Wang
In previous studies, the influence of gas phase and surface reactions on the growth of GaN was mainly calculated through simulations. In this study, a novel gas pre-decomposition device (GPDD) was designed to experimentally investigate the effects of gas phase and surface reactions on GaN growth by changing the length and height of the isolation plates (IPs). By varying the structure of the GPDD, the effects on the growth rate and thickness uniformity of the GaN films were studied. The growth rate of the GaN sample slowed with the extension of the IPs because the longer partition plates led to insufficient gas mixing and premature consumption of the precursor trimethylgallium (TMG). The use of GPDD simultaneously achieves high crystal quality and smooth surface morphology of the GaN film. Owing to the use of GPDD, the decomposition of TMG in the pyrolysis pathway was promoted, which suppressed Ga vacancies and C impurities, resulting in weak yellow luminescence bands in the photoluminescence. This study provides a comprehensive understanding of the chemical reaction mechanism of GaN and plays an important role in promoting the development of metal-organic chemical vapor deposition equipment.
在以往的研究中，气相和表面反应对氮化镓生长的影响主要是通过模拟计算得出的。本研究设计了一种新型气相预分解装置（GPDD），通过改变隔离板（IP）的长度和高度来实验研究气相和表面反应对氮化镓生长的影响。通过改变 GPDD 的结构，研究了对氮化镓薄膜生长速率和厚度均匀性的影响。由于较长的隔离板会导致气体混合不充分和前驱体三甲镓（TMG）的过早消耗，因此 GaN 样品的生长速度随着 IP 的延长而减慢。GPDD 的使用同时实现了 GaN 薄膜的高晶体质量和光滑表面形态。由于使用了 GPDD，促进了 TMG 在热解途径中的分解，从而抑制了 Ga 空位和 C 杂质，导致光致发光中出现微弱的黄色发光带。该研究全面了解了 GaN 的化学反应机理，对推动金属有机化学气相沉积设备的发展具有重要作用。
{"title":"Effect of gas pre-decomposition device on the growth of GaN epitaxial layer","authors":"Yazhou Li, Weizhen Yao, Zhanhong Ma, Shaoyan Yang, Xianglin Liu, Chengming Li and Zhanguo Wang","doi":"10.1088/1361-6641/ad4d5b","DOIUrl":"https://doi.org/10.1088/1361-6641/ad4d5b","url":null,"abstract":"In previous studies, the influence of gas phase and surface reactions on the growth of GaN was mainly calculated through simulations. In this study, a novel gas pre-decomposition device (GPDD) was designed to experimentally investigate the effects of gas phase and surface reactions on GaN growth by changing the length and height of the isolation plates (IPs). By varying the structure of the GPDD, the effects on the growth rate and thickness uniformity of the GaN films were studied. The growth rate of the GaN sample slowed with the extension of the IPs because the longer partition plates led to insufficient gas mixing and premature consumption of the precursor trimethylgallium (TMG). The use of GPDD simultaneously achieves high crystal quality and smooth surface morphology of the GaN film. Owing to the use of GPDD, the decomposition of TMG in the pyrolysis pathway was promoted, which suppressed Ga vacancies and C impurities, resulting in weak yellow luminescence bands in the photoluminescence. This study provides a comprehensive understanding of the chemical reaction mechanism of GaN and plays an important role in promoting the development of metal-organic chemical vapor deposition equipment.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"29 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141167497","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 : 2024-05-14DOI: 10.1088/1361-6641/ad4738
Zhi-Yuan Zheng and Ming-Ming Fan
Al doped α-GaOOH nanorod arrays were grown on FTO via hydrothermal processes by using gallium nitrate and aluminum nitrate mixed aqueous solutions with fixed 1:1 mole ratio as precursors. With increasing the gallium nitrate precursor concentrations, the Ga/Al atom ratios in nanorod arrays increase from 0.36 to 2.08, and the length becomes much longer from 650 nm to 1.04 μm. According to the binding energy difference between Ga 2p3/2 core level and its background in x-ray photoelectron spectroscopy, the bandgap is estimated to be around 5.3 ± 0.2 eV. Al doped α-GaOOH nanorod array/FTO photoelectrochemical photodetectors show enhanced self-powered solar-blind UV photodetection properties, with the decrease of Ga precursor concentrations. The maximum responsivity at 255 nm is 0.09 mA W−1, and the fastest response time can reach 0.05 s. The improved photoresponse speed is ascribed from much shorter transportation route, accelerated carrier recombination by recombination centers, and smaller charge transfer resistance at the α-GaOOH/electrolyte interface with decreasing the gallium nitrate precursor concentrations. The stability and responsivity should be further improved. Nevertheless, this work firstly demonstrates the realization of self-powered solar-blind UV photodetection for α-GaOOH nanorod arrays on FTO via Al doping.
{"title":"Fabrication of Al doped α-GaOOH nanorod arrays on FTO for self-powered photoelectrochemical solar-blind UV photodetectors","authors":"Zhi-Yuan Zheng and Ming-Ming Fan","doi":"10.1088/1361-6641/ad4738","DOIUrl":"https://doi.org/10.1088/1361-6641/ad4738","url":null,"abstract":"Al doped α-GaOOH nanorod arrays were grown on FTO via hydrothermal processes by using gallium nitrate and aluminum nitrate mixed aqueous solutions with fixed 1:1 mole ratio as precursors. With increasing the gallium nitrate precursor concentrations, the Ga/Al atom ratios in nanorod arrays increase from 0.36 to 2.08, and the length becomes much longer from 650 nm to 1.04 μm. According to the binding energy difference between Ga 2p3/2 core level and its background in x-ray photoelectron spectroscopy, the bandgap is estimated to be around 5.3 ± 0.2 eV. Al doped α-GaOOH nanorod array/FTO photoelectrochemical photodetectors show enhanced self-powered solar-blind UV photodetection properties, with the decrease of Ga precursor concentrations. The maximum responsivity at 255 nm is 0.09 mA W−1, and the fastest response time can reach 0.05 s. The improved photoresponse speed is ascribed from much shorter transportation route, accelerated carrier recombination by recombination centers, and smaller charge transfer resistance at the α-GaOOH/electrolyte interface with decreasing the gallium nitrate precursor concentrations. The stability and responsivity should be further improved. Nevertheless, this work firstly demonstrates the realization of self-powered solar-blind UV photodetection for α-GaOOH nanorod arrays on FTO via Al doping.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"7 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140926181","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 : 2024-04-24DOI: 10.1088/1361-6641/ad3d7c
Nguyen Hong Quang, Nguyen Thi Kim Thanh and Nguyen Que Huong
We theoretically study biexcitons and quadrons in quantum dots with parabolic confinement and give a complete comparison between the two excitations. The calculation of quadron and biexciton binding energies as functions of electron-to-hole confinement potentials and mass ratios, using the unrestricted Hartree–Fock method, shows the essential differences between biexcitons and quadrons. The crossover between the negative and positive binding energies is indicated. The effect of an external magnetic field on the quadron and biexciton binding energies has also been investigated. In addition, the crossover between anti-binding and binding of both excited quadron and biexciton states in a certain range of the electron-to-hole oscillator length ratios has been found.
{"title":"Biexcitons and quadrons in self-assembled quantum dots","authors":"Nguyen Hong Quang, Nguyen Thi Kim Thanh and Nguyen Que Huong","doi":"10.1088/1361-6641/ad3d7c","DOIUrl":"https://doi.org/10.1088/1361-6641/ad3d7c","url":null,"abstract":"We theoretically study biexcitons and quadrons in quantum dots with parabolic confinement and give a complete comparison between the two excitations. The calculation of quadron and biexciton binding energies as functions of electron-to-hole confinement potentials and mass ratios, using the unrestricted Hartree–Fock method, shows the essential differences between biexcitons and quadrons. The crossover between the negative and positive binding energies is indicated. The effect of an external magnetic field on the quadron and biexciton binding energies has also been investigated. In addition, the crossover between anti-binding and binding of both excited quadron and biexciton states in a certain range of the electron-to-hole oscillator length ratios has been found.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"30 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140805387","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 : 2024-04-15DOI: 10.1088/1361-6641/ad3a93
Yujie Gao, Xun Hu, Lingli Zhu, Na Gao, Rui Zhou, Yaping Wu, Kai Huang, Shuping Li, Junyong Kang, Rong Zhang
High-efficiency deep-ultraviolet (DUV) micro light-emitting diodes (LEDs) are explored for inspiring development in numerous fields, such as non-line-of-sight solar-blind communication, optical pumping, and maskless lithography. In this study, we performed FDTD and SimuLED calculations to investigate the optimized DUV micro-LED structure geometry for high light extraction efficiency (LEE) by designing different mesa structures, including square, hexagonal, and circular geometries of micro-LEDs emitted at a wavelength of 275 nm. The results showed that a circular mesa of 5 μm diameter achieved a LEE of 27% from the bottom and sidewall emissions of as-prepared DUV micro-LED. And both the near- and far-field transverse magnetic polarized light intensities were enhanced by a factor of 1.5 over the square and hexagonal mesas. Meanwhile, the transverse electric (TE) polarized light of the circular mesa structure was enhanced and concentrated along the normal direction. Moreover, the internal quantum efficiency (IQE) of circular mesas with varied sizes was comprehensively investigated in the interactions of the thermal and electric fields. An AlGaN-based DUV micro-LED with a diameter of 5 μm was found to obtain the highest IQE owing to a high current-density distribution and its self-heating properties, thereby achieving a sufficiently high external quantum efficiency of 26.75%. This study provides a comprehensive technical report, including electrical, thermal, and optical analyses, and a new perspective for developing high-efficiency, high-performance DUV micro-LEDs in practical applications.
高效深紫外（DUV）微型发光二极管（LED）在许多领域都得到了令人鼓舞的发展，例如非视线太阳盲通信、光泵浦和无掩模光刻。在这项研究中，我们进行了 FDTD 和 SimuLED 计算，通过设计不同的网格结构（包括在 275 nm 波长处发射的微型 LED 的正方形、六边形和圆形几何结构）来研究优化的 DUV 微型 LED 结构几何形状，以实现高光萃取效率（LEE）。结果表明，直径为 5 μm 的圆形网格从制备好的 DUV 微型 LED 的底部和侧壁发射的萃取效率达到了 27%。近场和远场横向磁偏振光强度都比正方形和六边形网格增强了 1.5 倍。同时，圆形网格结构的横向电（TE）偏振光沿法线方向增强并集中。此外，在热场和电场的相互作用下，还全面研究了不同尺寸圆网格的内部量子效率（IQE）。研究发现，直径为 5 μm 的 AlGaN 基 DUV 微型 LED 因其高电流密度分布和自加热特性而获得了最高的 IQE，从而实现了 26.75% 的足够高的外部量子效率。这项研究提供了一份全面的技术报告，包括电学、热学和光学分析，为在实际应用中开发高效率、高性能的紫外微型 LED 提供了新的视角。
{"title":"Enhancing external quantum efficiency of deep ultraviolet micro-leds through geometry design and multi-physics field coupling analysis","authors":"Yujie Gao, Xun Hu, Lingli Zhu, Na Gao, Rui Zhou, Yaping Wu, Kai Huang, Shuping Li, Junyong Kang, Rong Zhang","doi":"10.1088/1361-6641/ad3a93","DOIUrl":"https://doi.org/10.1088/1361-6641/ad3a93","url":null,"abstract":"High-efficiency deep-ultraviolet (DUV) micro light-emitting diodes (LEDs) are explored for inspiring development in numerous fields, such as non-line-of-sight solar-blind communication, optical pumping, and maskless lithography. In this study, we performed FDTD and SimuLED calculations to investigate the optimized DUV micro-LED structure geometry for high light extraction efficiency (LEE) by designing different mesa structures, including square, hexagonal, and circular geometries of micro-LEDs emitted at a wavelength of 275 nm. The results showed that a circular mesa of 5 <italic toggle=\"yes\">μ</italic>m diameter achieved a LEE of 27% from the bottom and sidewall emissions of as-prepared DUV micro-LED. And both the near- and far-field transverse magnetic polarized light intensities were enhanced by a factor of 1.5 over the square and hexagonal mesas. Meanwhile, the transverse electric (TE) polarized light of the circular mesa structure was enhanced and concentrated along the normal direction. Moreover, the internal quantum efficiency (IQE) of circular mesas with varied sizes was comprehensively investigated in the interactions of the thermal and electric fields. An AlGaN-based DUV micro-LED with a diameter of 5 <italic toggle=\"yes\">μ</italic>m was found to obtain the highest IQE owing to a high current-density distribution and its self-heating properties, thereby achieving a sufficiently high external quantum efficiency of 26.75%. This study provides a comprehensive technical report, including electrical, thermal, and optical analyses, and a new perspective for developing high-efficiency, high-performance DUV micro-LEDs in practical applications.","PeriodicalId":21585,"journal":{"name":"Semiconductor Science and Technology","volume":"22 1","pages":""},"PeriodicalIF":1.9,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140608869","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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