Pub Date : 2022-06-01DOI: 10.1109/CSW55288.2022.9930397
R. Oshima, T. Sugaya
In III-V solar cells, much research has been conducted to improve the conversion efficiency by applying a rear heterojunction (RHJ) structure as a mean of controlling the built-in potential. In this work, a p-type Al0.48In0.52As rear heterojunction (RHJ) emitter was employed in Ga0.47In0.53As solar cells with 0.75 eV in bandgap grown by molecular beam epitaxy. A typical RHJ solar cell structure showed increase in reverse saturation current density (J0) since the positions of the pn interface and the heterointerface are the same. On the other hand, the introduction of an appropriate thicknesses of n-AlInAs spacer layer between p-AlInAs emitter and n-GaInAs base can separate each interface position and was found to reduce J0 leading to improved VOC and FF. In addition, the backside reflective structure was employed to optimized RHJ solar cells, showing the highest conversion efficiency of 15.38% among the reported values in the literature so far due to promoted light trapping.
{"title":"AlInAs heterojunction emitter for highly efficient inverted GaInAs solar cells grown by molecular beam epitaxy","authors":"R. Oshima, T. Sugaya","doi":"10.1109/CSW55288.2022.9930397","DOIUrl":"https://doi.org/10.1109/CSW55288.2022.9930397","url":null,"abstract":"In III-V solar cells, much research has been conducted to improve the conversion efficiency by applying a rear heterojunction (RHJ) structure as a mean of controlling the built-in potential. In this work, a p-type Al0.48In0.52As rear heterojunction (RHJ) emitter was employed in Ga0.47In0.53As solar cells with 0.75 eV in bandgap grown by molecular beam epitaxy. A typical RHJ solar cell structure showed increase in reverse saturation current density (J0) since the positions of the pn interface and the heterointerface are the same. On the other hand, the introduction of an appropriate thicknesses of n-AlInAs spacer layer between p-AlInAs emitter and n-GaInAs base can separate each interface position and was found to reduce J0 leading to improved VOC and FF. In addition, the backside reflective structure was employed to optimized RHJ solar cells, showing the highest conversion efficiency of 15.38% among the reported values in the literature so far due to promoted light trapping.","PeriodicalId":382443,"journal":{"name":"2022 Compound Semiconductor Week (CSW)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114858385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-01DOI: 10.1109/CSW55288.2022.9930390
Syed M. N. Hasan, Arnob Ghosh, S. Sadaf, S. Arafin
The optical emission properties of axial InGaN/GaN nanowires with different InGaN quantum disk (Qdisk) thicknesses are experimentally investigated using a combination of photoluminescence (PL) and cathodoluminescence (CL) spectroscopy. Both the spectroscopic measurements from the average InGaN Qdisk-related emissions reveal the presence of built-in piezoelectric strain as evidenced by the luminescence blueshift with increasing pump signal. To determine the material compositions and their spatial uniformity, transmission electron microscopy with energy-dispersive x-ray spectroscopy were also performed. Systematic analysis of the optical emission properties with the change of Qdisk thickness serves to advance the understanding of, in general, III-nitride nanostructures for the implementation of classical and non-classical optoelectronic devices.
{"title":"Influence of InGaN Quantum Disk Thickness on the Optical Properties of GaN Nanowires","authors":"Syed M. N. Hasan, Arnob Ghosh, S. Sadaf, S. Arafin","doi":"10.1109/CSW55288.2022.9930390","DOIUrl":"https://doi.org/10.1109/CSW55288.2022.9930390","url":null,"abstract":"The optical emission properties of axial InGaN/GaN nanowires with different InGaN quantum disk (Qdisk) thicknesses are experimentally investigated using a combination of photoluminescence (PL) and cathodoluminescence (CL) spectroscopy. Both the spectroscopic measurements from the average InGaN Qdisk-related emissions reveal the presence of built-in piezoelectric strain as evidenced by the luminescence blueshift with increasing pump signal. To determine the material compositions and their spatial uniformity, transmission electron microscopy with energy-dispersive x-ray spectroscopy were also performed. Systematic analysis of the optical emission properties with the change of Qdisk thickness serves to advance the understanding of, in general, III-nitride nanostructures for the implementation of classical and non-classical optoelectronic devices.","PeriodicalId":382443,"journal":{"name":"2022 Compound Semiconductor Week (CSW)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127007605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-01DOI: 10.1109/CSW55288.2022.9930409
A. Strömberg, B. Manavaimaran, L. Srinivasan, S. Lourdudoss, Y. Sun
High crystal quality GaAsP/Si fabricated by cost effective heteroepitaxial technology is promising to realize low-cost Si based tandem solar cell with efficiency higher than 30%. In this work, epitaxial lateral overgrowth (ELOG) of GaAsP/GaAs and GaAsP/GaAs/Si by hydride vapor phase epitaxy (HVPE) and their properties are studied by photoluminescence (PL) mapping. High crystal quality ELOG GaAsP/Si is obtained with enhanced PL intensity and narrow line width indicating reduced defect density provided by ELOG approach.
{"title":"Epitaxial lateral overgrowth of GaAsP/Si for tandem solar cell","authors":"A. Strömberg, B. Manavaimaran, L. Srinivasan, S. Lourdudoss, Y. Sun","doi":"10.1109/CSW55288.2022.9930409","DOIUrl":"https://doi.org/10.1109/CSW55288.2022.9930409","url":null,"abstract":"High crystal quality GaAsP/Si fabricated by cost effective heteroepitaxial technology is promising to realize low-cost Si based tandem solar cell with efficiency higher than 30%. In this work, epitaxial lateral overgrowth (ELOG) of GaAsP/GaAs and GaAsP/GaAs/Si by hydride vapor phase epitaxy (HVPE) and their properties are studied by photoluminescence (PL) mapping. High crystal quality ELOG GaAsP/Si is obtained with enhanced PL intensity and narrow line width indicating reduced defect density provided by ELOG approach.","PeriodicalId":382443,"journal":{"name":"2022 Compound Semiconductor Week (CSW)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134181297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-01DOI: 10.1109/CSW55288.2022.9930118
Y. liu, Yu-Tzu Liao, Jian-jang Huang, Yuh‐Renn Wu
In this work, the design of double heterojunction bipolar transistors (DHBTs) is to improve the unit current gain cutoff frequency (fT). We proposed using a compositionally graded emitter and adding a ledge layer between the base and the emitter to enhance fT. These results exhibit the high fT of these DHBTs.
{"title":"Design of AlInAs/GaAsSb/InGaAsSb Double Heterojunction Bipolar Transistors for The Unit Current Gain Cutoff Frequency of 850GHz","authors":"Y. liu, Yu-Tzu Liao, Jian-jang Huang, Yuh‐Renn Wu","doi":"10.1109/CSW55288.2022.9930118","DOIUrl":"https://doi.org/10.1109/CSW55288.2022.9930118","url":null,"abstract":"In this work, the design of double heterojunction bipolar transistors (DHBTs) is to improve the unit current gain cutoff frequency (fT). We proposed using a compositionally graded emitter and adding a ledge layer between the base and the emitter to enhance fT. These results exhibit the high fT of these DHBTs.","PeriodicalId":382443,"journal":{"name":"2022 Compound Semiconductor Week (CSW)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131002070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-01DOI: 10.1109/CSW55288.2022.9930378
P. Runge, S. Seifert
A generalized for the wavelength dependent refractive index in the transparent and absorbing SWIR wavelength regime of In1-x-yAlyGaxAs compound semiconductors is presented, being lattice-matched to InP. The model is derived from ellipsometric measurements of eight different In1-x-yAlyGaxAs grown semiconductor compositions.
{"title":"Revised Refractive Index of InP-Lattice Matched In1-x-yAlyGaxAs","authors":"P. Runge, S. Seifert","doi":"10.1109/CSW55288.2022.9930378","DOIUrl":"https://doi.org/10.1109/CSW55288.2022.9930378","url":null,"abstract":"A generalized for the wavelength dependent refractive index in the transparent and absorbing SWIR wavelength regime of In<inf>1-x-y</inf>Al<inf>y</inf>Ga<inf>x</inf>As compound semiconductors is presented, being lattice-matched to InP. The model is derived from ellipsometric measurements of eight different In<inf>1-x-y</inf>Al<inf>y</inf>Ga<inf>x</inf>As grown semiconductor compositions.","PeriodicalId":382443,"journal":{"name":"2022 Compound Semiconductor Week (CSW)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115182344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-01DOI: 10.1109/CSW55288.2022.9930117
C. Wurm, H. Collins, N. Hatui, Weiyi Li, S. Pasayat, R. Hamwey, K. Sun, I. Sayed, K. Khan, E. Ahmadi, S. Keller, U. Mishra
Device-quality, relaxed InGaN substrates has been a topic of great interest, particularly for longer wavelength optoelectronics. This work demonstrates MBE-grown In0.2Ga0.8N with a strain relaxation of 60% corresponding to an equivalently fully relaxed In-composition of 12% achieved by growing on a GaN-on-porous GaN pseudo-substrate (PS). The surface morphology of this film was found to be free of V-defects on the surface and with a threading dislocation density comparable to that of the GaN layers beneath.
{"title":"Demonstration of device-quality InGaN grown on porous GaN tiles by MBE with an in-plane lattice constant equivalent to fully relaxed In0.12Ga0.88N","authors":"C. Wurm, H. Collins, N. Hatui, Weiyi Li, S. Pasayat, R. Hamwey, K. Sun, I. Sayed, K. Khan, E. Ahmadi, S. Keller, U. Mishra","doi":"10.1109/CSW55288.2022.9930117","DOIUrl":"https://doi.org/10.1109/CSW55288.2022.9930117","url":null,"abstract":"Device-quality, relaxed InGaN substrates has been a topic of great interest, particularly for longer wavelength optoelectronics. This work demonstrates MBE-grown In0.2Ga0.8N with a strain relaxation of 60% corresponding to an equivalently fully relaxed In-composition of 12% achieved by growing on a GaN-on-porous GaN pseudo-substrate (PS). The surface morphology of this film was found to be free of V-defects on the surface and with a threading dislocation density comparable to that of the GaN layers beneath.","PeriodicalId":382443,"journal":{"name":"2022 Compound Semiconductor Week (CSW)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121853721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-01DOI: 10.1109/csw55288.2022.9930436
P. Bagheri, Cristyan Quiñones-García, P. Reddy, S. Mita, R. Collazo, Z. Sitar
High mobility of 270 cm2/Vs and free electron concentration as high as 1015 cm-3 were achieved in Si doped AlN grown on AlN single crystal via point defect management. CN incorporation in homoepitaxial film was successfully reduced by increasing the V/III and growth temperature as two growth knobs during the MOCVD growth. This work demonstrates the Si doping limit in AlN as low as mid-1017 cm-3 via Chemical Potential Control during the deposition process. CN and threading dislocations are two acceptor-type compensators determining the low doping limit in n-type AlN. Suppression of these defects to further improve the low doping limit (minimum achievable carrier concentration along with the maximum mobility) opens up pathways for realization of AlN-based power electronic devices.
{"title":"Controllable N-type Doping In Ultra-Wide Bandgap AlN By Chemical Potential Control","authors":"P. Bagheri, Cristyan Quiñones-García, P. Reddy, S. Mita, R. Collazo, Z. Sitar","doi":"10.1109/csw55288.2022.9930436","DOIUrl":"https://doi.org/10.1109/csw55288.2022.9930436","url":null,"abstract":"High mobility of 270 cm2/Vs and free electron concentration as high as 1015 cm-3 were achieved in Si doped AlN grown on AlN single crystal via point defect management. CN incorporation in homoepitaxial film was successfully reduced by increasing the V/III and growth temperature as two growth knobs during the MOCVD growth. This work demonstrates the Si doping limit in AlN as low as mid-1017 cm-3 via Chemical Potential Control during the deposition process. CN and threading dislocations are two acceptor-type compensators determining the low doping limit in n-type AlN. Suppression of these defects to further improve the low doping limit (minimum achievable carrier concentration along with the maximum mobility) opens up pathways for realization of AlN-based power electronic devices.","PeriodicalId":382443,"journal":{"name":"2022 Compound Semiconductor Week (CSW)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127103013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-01DOI: 10.1109/CSW55288.2022.9930366
T. Gotow, T. Arai, T. Aota, Y. Miyamoto
The application of a wet treatment using tetramethylammonium hydroxide (TMAH) is expected to reduce process damage related to dry etching and increase the simplicity of the isolation process of GaN high electron mobility transistors (HEMTs). This study investigates the isolation process using TMAH and fabricates N-polar GaN HEMT devices. Based on the results, there are sufficient resistance values exceeding 1011 Ω between the isolation gaps treated with the TMAH treatment. For the fabricated N-polar GaN HEMTs, values of IDmax = 1.13 A/mm and Ron = 3.5 Ωmm were obtained, demonstrating that the application of TMAH is useful as a device separation technique for N-polar GaN HEMTs.
{"title":"Evaluation of TMAH treatment for isolation process of N-polar GaN HEMTs","authors":"T. Gotow, T. Arai, T. Aota, Y. Miyamoto","doi":"10.1109/CSW55288.2022.9930366","DOIUrl":"https://doi.org/10.1109/CSW55288.2022.9930366","url":null,"abstract":"The application of a wet treatment using tetramethylammonium hydroxide (TMAH) is expected to reduce process damage related to dry etching and increase the simplicity of the isolation process of GaN high electron mobility transistors (HEMTs). This study investigates the isolation process using TMAH and fabricates N-polar GaN HEMT devices. Based on the results, there are sufficient resistance values exceeding 1011 Ω between the isolation gaps treated with the TMAH treatment. For the fabricated N-polar GaN HEMTs, values of IDmax = 1.13 A/mm and Ron = 3.5 Ωmm were obtained, demonstrating that the application of TMAH is useful as a device separation technique for N-polar GaN HEMTs.","PeriodicalId":382443,"journal":{"name":"2022 Compound Semiconductor Week (CSW)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127144002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-01DOI: 10.1109/CSW55288.2022.9930377
R. Kaneko, R. Katsuhara, R. Yabuki, A. Matsumoto, K. Akahane, Y. Matsushima, H. Ishikawa, K. Utaka
Distributed feedback (DFB) lasers with side gratings were fabricated by a novel method of two step etching using 1550nm InAs/InGaAlAs quantum dot (QD) wafers grown on InP(311)B substrates with strain compensation technique, and room temperature continuous wave (CW) single-mode operation with a side mode suppression ratio (SMSR) of 39 dB was achieved by AR/HR facet coating. The threshold current density was 2.33 kA/cm2, and high temperature operation up to 80 °C was also achieved without heat dissipation treatment. The characteristic temperature coefficient was 113 K, and the wavelength shift was 0.05 nm/K.
{"title":"Fabrication and Temperature Characteristics of 1550nm InAs/InGaAlAs Quantum Dot Distributed Feedback Lasers with Side Grating","authors":"R. Kaneko, R. Katsuhara, R. Yabuki, A. Matsumoto, K. Akahane, Y. Matsushima, H. Ishikawa, K. Utaka","doi":"10.1109/CSW55288.2022.9930377","DOIUrl":"https://doi.org/10.1109/CSW55288.2022.9930377","url":null,"abstract":"Distributed feedback (DFB) lasers with side gratings were fabricated by a novel method of two step etching using 1550nm InAs/InGaAlAs quantum dot (QD) wafers grown on InP(311)B substrates with strain compensation technique, and room temperature continuous wave (CW) single-mode operation with a side mode suppression ratio (SMSR) of 39 dB was achieved by AR/HR facet coating. The threshold current density was 2.33 kA/cm2, and high temperature operation up to 80 °C was also achieved without heat dissipation treatment. The characteristic temperature coefficient was 113 K, and the wavelength shift was 0.05 nm/K.","PeriodicalId":382443,"journal":{"name":"2022 Compound Semiconductor Week (CSW)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126273147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-01DOI: 10.1109/CSW55288.2022.9930123
Yong Zhang
Confocal micro-Raman microscopy performed in the transparent spectral region of a semiconductor can, in principle, be used for operando three-dimensional (3D) thermometry with optical diffraction-limit spatial resolution. However, when applied to high-power GaN-based light-emitting diodes (LEDs), the applicability is hindered by the secondary but nevertheless relatively strong electroluminescence in the visible spectral region that can overwhelm the Raman signal. We develop a “split-time-window” scheme that can mimic the continuous wave operation but without the interference of the secondary emission, which allows us to carry out noninvasive 3D temperature profiling and comprehensive thermal analyses of the whole device at any operation current. The technique is applied to an (InxGa1-x)N/GaN LED to extract its 3D temperature distribution when operated at 350 mA with μm-scale resolution when using a 532-nm laser. This technique allows for in-operando monitoring whether hot spots are associated with device failure. If further correlating with HRSTM investigation, one can obtain the structure information of the hot spots in the device and thus help to determine the device failure mechanism. The approach is equally applicable to other devices, such as power electronic devices.
{"title":"In Operando Micro-Raman 3-D Thermometry with Diffraction-Limit Spatial Resolution for GaN-based (Opto)electronic Devices","authors":"Yong Zhang","doi":"10.1109/CSW55288.2022.9930123","DOIUrl":"https://doi.org/10.1109/CSW55288.2022.9930123","url":null,"abstract":"Confocal micro-Raman microscopy performed in the transparent spectral region of a semiconductor can, in principle, be used for operando three-dimensional (3D) thermometry with optical diffraction-limit spatial resolution. However, when applied to high-power GaN-based light-emitting diodes (LEDs), the applicability is hindered by the secondary but nevertheless relatively strong electroluminescence in the visible spectral region that can overwhelm the Raman signal. We develop a “split-time-window” scheme that can mimic the continuous wave operation but without the interference of the secondary emission, which allows us to carry out noninvasive 3D temperature profiling and comprehensive thermal analyses of the whole device at any operation current. The technique is applied to an (InxGa1-x)N/GaN LED to extract its 3D temperature distribution when operated at 350 mA with μm-scale resolution when using a 532-nm laser. This technique allows for in-operando monitoring whether hot spots are associated with device failure. If further correlating with HRSTM investigation, one can obtain the structure information of the hot spots in the device and thus help to determine the device failure mechanism. The approach is equally applicable to other devices, such as power electronic devices.","PeriodicalId":382443,"journal":{"name":"2022 Compound Semiconductor Week (CSW)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126393586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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