Pub Date : 2012-10-02DOI: 10.1109/NUSOD.2012.6316546
J. Piprek
High-power broad-area laser diodes often suffer from a widening of the lateral far-field with increasing current, called thermal blooming. This effect is mainly caused by the non-uniform self-heating of the laser and it has been studied for several decades. For the first time, this paper presents a self-consistent electro-thermal-optical simulation of thermal blooming, including all relevant physical mechanisms. The results are in good agreement with previous measurements and reveal the blooming mechanism in detail. Common mistakes in the experimental determination of the internal temperature rise are also discussed.
{"title":"Self-consistent electro-thermal-optical simulation of thermal blooming in broad-area lasers","authors":"J. Piprek","doi":"10.1109/NUSOD.2012.6316546","DOIUrl":"https://doi.org/10.1109/NUSOD.2012.6316546","url":null,"abstract":"High-power broad-area laser diodes often suffer from a widening of the lateral far-field with increasing current, called thermal blooming. This effect is mainly caused by the non-uniform self-heating of the laser and it has been studied for several decades. For the first time, this paper presents a self-consistent electro-thermal-optical simulation of thermal blooming, including all relevant physical mechanisms. The results are in good agreement with previous measurements and reveal the blooming mechanism in detail. Common mistakes in the experimental determination of the internal temperature rise are also discussed.","PeriodicalId":337826,"journal":{"name":"2012 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114973740","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 : 2012-10-02DOI: 10.1109/NUSOD.2012.6316545
Chia-Hua Huang, Hung-Lung Cheng
The performance of Cu(In, Ga)Se2 (CIGS) solar cells with the incorporation of sulfur into the surface region of the absorbers has been studied by numerical simulation. The impacts of sulfur contents and thickness of sulfurized layers in the surface region of absorbers on the performance were evaluated. The results show that the incorporation of sulfur in the CIGS films enhances the open-circuit voltage (VOC), but concurrently leads to the reduction in short-circuit current density (JSC). The S/(S+Se) ratios of below 0.2 could improve the cell performance for all thickness of sulfurized layers in this study. For S/(S+Se) ratios of 0.1-0.5, the thickness of 200nm was suggested to enhance the efficiency of devices.
{"title":"Effects of sulfur incorporation into absorbers of CIGS solar cells studied by numerical analysis","authors":"Chia-Hua Huang, Hung-Lung Cheng","doi":"10.1109/NUSOD.2012.6316545","DOIUrl":"https://doi.org/10.1109/NUSOD.2012.6316545","url":null,"abstract":"The performance of Cu(In, Ga)Se2 (CIGS) solar cells with the incorporation of sulfur into the surface region of the absorbers has been studied by numerical simulation. The impacts of sulfur contents and thickness of sulfurized layers in the surface region of absorbers on the performance were evaluated. The results show that the incorporation of sulfur in the CIGS films enhances the open-circuit voltage (VOC), but concurrently leads to the reduction in short-circuit current density (JSC). The S/(S+Se) ratios of below 0.2 could improve the cell performance for all thickness of sulfurized layers in this study. For S/(S+Se) ratios of 0.1-0.5, the thickness of 200nm was suggested to enhance the efficiency of devices.","PeriodicalId":337826,"journal":{"name":"2012 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129591483","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 : 2012-10-02DOI: 10.1109/NUSOD.2012.6316531
B. Witzigmann, M. Deppner, F. Romer
Light Emitting Diodes (LEDs) have become an attractive concept as efficient light sources. In this contribution, the electro-optical performance of Ill-nitride based core-shell nanorod LEDs is investigated by detailed simulation. In contrast to their planar counterparts, they possess increased active region area on small footprint, non-polar active regions with c-plane vertical growth, and form horizontal two-dimensional active photonic crystals for the optical extraction process.
{"title":"InGaN nanorod LEDs: A performance assessment","authors":"B. Witzigmann, M. Deppner, F. Romer","doi":"10.1109/NUSOD.2012.6316531","DOIUrl":"https://doi.org/10.1109/NUSOD.2012.6316531","url":null,"abstract":"Light Emitting Diodes (LEDs) have become an attractive concept as efficient light sources. In this contribution, the electro-optical performance of Ill-nitride based core-shell nanorod LEDs is investigated by detailed simulation. In contrast to their planar counterparts, they possess increased active region area on small footprint, non-polar active regions with c-plane vertical growth, and form horizontal two-dimensional active photonic crystals for the optical extraction process.","PeriodicalId":337826,"journal":{"name":"2012 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114757505","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 : 2012-10-02DOI: 10.1109/NUSOD.2012.6316547
Y. B. Shi, Z. Akšamija, I. Knezevic
One of the limiting factors for the room-temperature continuous-wave (RT-cw) operation of quantum cascade lasers (QCLs) is the high temperature in the active region that stems from the high electrical power and poor heat extraction [1]. In order to simulate the thermal behavior of QCLs, the heat diffusion equation with appropriate source and boundary conditions needs to be solved. However, the heat generation rate of the active region under a given bias is both space- and temperature-dependent. In this paper, we present a method of extracting the heat generation rate by recording the electron-optical phonon scattering during the ensemble Monte Carlo (EMC) simulation of electron transport under different temperatures. The extracted nonlinear heat source together with appropriate thermal conductivity models enable self-consistent calculation of temperature distribution throughout QCLs. We apply the thermal model to investigate the cross-plane temperature distribution of a 9.4 μm infrared GaAs-based QCL [2]. The nonlinear effects stemming from the temperature dependence of thermal conductivity and the heat generation rate are studied.
{"title":"Thermal simulation of GaAs-based midinfrared quantum cascade lasers","authors":"Y. B. Shi, Z. Akšamija, I. Knezevic","doi":"10.1109/NUSOD.2012.6316547","DOIUrl":"https://doi.org/10.1109/NUSOD.2012.6316547","url":null,"abstract":"One of the limiting factors for the room-temperature continuous-wave (RT-cw) operation of quantum cascade lasers (QCLs) is the high temperature in the active region that stems from the high electrical power and poor heat extraction [1]. In order to simulate the thermal behavior of QCLs, the heat diffusion equation with appropriate source and boundary conditions needs to be solved. However, the heat generation rate of the active region under a given bias is both space- and temperature-dependent. In this paper, we present a method of extracting the heat generation rate by recording the electron-optical phonon scattering during the ensemble Monte Carlo (EMC) simulation of electron transport under different temperatures. The extracted nonlinear heat source together with appropriate thermal conductivity models enable self-consistent calculation of temperature distribution throughout QCLs. We apply the thermal model to investigate the cross-plane temperature distribution of a 9.4 μm infrared GaAs-based QCL [2]. The nonlinear effects stemming from the temperature dependence of thermal conductivity and the heat generation rate are studied.","PeriodicalId":337826,"journal":{"name":"2012 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125189199","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 : 2012-10-02DOI: 10.1109/NUSOD.2012.6316521
F. F. Masouleh, N. Das, H. Mashayekhi
We use finite difference time-domain (FDTD) method to calculate the light absorption enhancement of nano-grating assisted metal-semiconductor-metal photo-detectors (MSM-PDs). The simulated results show that the light absorption enhancement of nano-grating assisted MSM-PD is ~9-times better than conventional MSM-PD.
{"title":"Impact of duty cycle and nano-grating height on the light absorption of plasmonics-based MSM photodetectors","authors":"F. F. Masouleh, N. Das, H. Mashayekhi","doi":"10.1109/NUSOD.2012.6316521","DOIUrl":"https://doi.org/10.1109/NUSOD.2012.6316521","url":null,"abstract":"We use finite difference time-domain (FDTD) method to calculate the light absorption enhancement of nano-grating assisted metal-semiconductor-metal photo-detectors (MSM-PDs). The simulated results show that the light absorption enhancement of nano-grating assisted MSM-PD is ~9-times better than conventional MSM-PD.","PeriodicalId":337826,"journal":{"name":"2012 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125300382","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 : 2012-10-02DOI: 10.1109/NUSOD.2012.6316494
J. Liang, W. D. Hu, X. Chen, C. Xia, L. Cheng
The structure parameters and illumination condition for InGaP/GaAs/InGaAs triple-junction solar cells grown on GaAs substrate have been numerically studied to search the optimal point of device performance. The dependences of conversion efficiency, I-V curves, and band diagram on the structure parameters and illumination condition have been investigated. Our work shows that the performances are largely dependent on the geometric design of device and the optimal parameters are extracted.
{"title":"Numerical simulation of high-efficiency InGaP/GaAs/InGaAs triple-junction solar cells grown on GaAs substrate","authors":"J. Liang, W. D. Hu, X. Chen, C. Xia, L. Cheng","doi":"10.1109/NUSOD.2012.6316494","DOIUrl":"https://doi.org/10.1109/NUSOD.2012.6316494","url":null,"abstract":"The structure parameters and illumination condition for InGaP/GaAs/InGaAs triple-junction solar cells grown on GaAs substrate have been numerically studied to search the optimal point of device performance. The dependences of conversion efficiency, I-V curves, and band diagram on the structure parameters and illumination condition have been investigated. Our work shows that the performances are largely dependent on the geometric design of device and the optimal parameters are extracted.","PeriodicalId":337826,"journal":{"name":"2012 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129640518","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 : 2012-10-02DOI: 10.1109/NUSOD.2012.6316498
Sang-Pil Han, Namje Kim, H. Ryu, H. Ko, J. Park, M. Jeon, K. Park
We demonstrate a portable terahertz (THz) spectrometer and imaging system. Absorption lines of water vapor in the free space are clearly observed by using the THz system. A THz imaging of a medical knife behind a poly-ethylene is finely measured by the same THz system as well.
{"title":"Portable 1.55μm terahertz spectrometer and imaging system","authors":"Sang-Pil Han, Namje Kim, H. Ryu, H. Ko, J. Park, M. Jeon, K. Park","doi":"10.1109/NUSOD.2012.6316498","DOIUrl":"https://doi.org/10.1109/NUSOD.2012.6316498","url":null,"abstract":"We demonstrate a portable terahertz (THz) spectrometer and imaging system. Absorption lines of water vapor in the free space are clearly observed by using the THz system. A THz imaging of a medical knife behind a poly-ethylene is finely measured by the same THz system as well.","PeriodicalId":337826,"journal":{"name":"2012 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129800284","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 : 2012-10-02DOI: 10.1109/NUSOD.2012.6316508
L. Li, Q. Weng, J. Wen, D. Xiong
We present an equivalent circuit model for AlGaAs/GaAs long wavelength quantum well infrared photodetectors (LW-QWIPs). Bias dependence of the dark current and photocurrent is described with the aid of analogue circuit modelling technique in TINA software. This model can be integrated with the readout circuit for the whole device circuit optimization further. The temperature dependence of dark current has also been incorporated into this circuit model. The designed parameters of the LW-QWIPs can be fed into this model as user-defined inputs to simulate the detector performance. The obtained results agree well with the experimental measurements.
{"title":"An equivalent circuit model for the long-wavelength quantum well infrared detectors","authors":"L. Li, Q. Weng, J. Wen, D. Xiong","doi":"10.1109/NUSOD.2012.6316508","DOIUrl":"https://doi.org/10.1109/NUSOD.2012.6316508","url":null,"abstract":"We present an equivalent circuit model for AlGaAs/GaAs long wavelength quantum well infrared photodetectors (LW-QWIPs). Bias dependence of the dark current and photocurrent is described with the aid of analogue circuit modelling technique in TINA software. This model can be integrated with the readout circuit for the whole device circuit optimization further. The temperature dependence of dark current has also been incorporated into this circuit model. The designed parameters of the LW-QWIPs can be fed into this model as user-defined inputs to simulate the detector performance. The obtained results agree well with the experimental measurements.","PeriodicalId":337826,"journal":{"name":"2012 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129513744","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 : 2012-10-02DOI: 10.1109/NUSOD.2012.6316533
S. Hung, C. Hung
We present a new semiellipsoid microlens fabrication method using the lift-off and alignment exposure processes. The lift-off method is used to create an elliptical copper base before the thermal reflow process. During the photoresist thermal reflow process, the elliptical base can precisely define the bottom shape of the liquid photoresist. The prolate spheroid approximation method is developed to estimate the thickness of elliptic photoresist column required by the semiellipsoid microlens of a certain height, with the error being controlled within ±3%.
{"title":"An evaluation of photoresist thickness for semiellipsoid microlens fabrication before thermal reflow using the prolate spheroid approximation","authors":"S. Hung, C. Hung","doi":"10.1109/NUSOD.2012.6316533","DOIUrl":"https://doi.org/10.1109/NUSOD.2012.6316533","url":null,"abstract":"We present a new semiellipsoid microlens fabrication method using the lift-off and alignment exposure processes. The lift-off method is used to create an elliptical copper base before the thermal reflow process. During the photoresist thermal reflow process, the elliptical base can precisely define the bottom shape of the liquid photoresist. The prolate spheroid approximation method is developed to estimate the thickness of elliptic photoresist column required by the semiellipsoid microlens of a certain height, with the error being controlled within ±3%.","PeriodicalId":337826,"journal":{"name":"2012 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122049095","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 : 2012-10-02DOI: 10.1109/NUSOD.2012.6316558
Cheng Zhang, Mingsen Deng, Shaohong Cai
The mechanical properties and electronic structure of graphene nanoribbons (GNRs) which modified atoms or molecular groups on the zigzag edges can be tuned under the uniaxial tensile strain for application on the electronic devices. We study the elastic and plastic deformation of GNRs. The modified zigzag edges play a key role in tense force, elastic constant, critical point (the critical point of elastic and plastic deformation) and the energy gaps. In particular, it is shown that the energy gap of edge-modification GNRs can be strongly modified under uniaxial tensile strain. This way, offer new opportunities to electronic transport and force-electronic devices for next-generation electronics.
{"title":"Strain-induced modulation of mechanical properties and electronic structure of edge-modification graphene nanoribbons","authors":"Cheng Zhang, Mingsen Deng, Shaohong Cai","doi":"10.1109/NUSOD.2012.6316558","DOIUrl":"https://doi.org/10.1109/NUSOD.2012.6316558","url":null,"abstract":"The mechanical properties and electronic structure of graphene nanoribbons (GNRs) which modified atoms or molecular groups on the zigzag edges can be tuned under the uniaxial tensile strain for application on the electronic devices. We study the elastic and plastic deformation of GNRs. The modified zigzag edges play a key role in tense force, elastic constant, critical point (the critical point of elastic and plastic deformation) and the energy gaps. In particular, it is shown that the energy gap of edge-modification GNRs can be strongly modified under uniaxial tensile strain. This way, offer new opportunities to electronic transport and force-electronic devices for next-generation electronics.","PeriodicalId":337826,"journal":{"name":"2012 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125496890","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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