The Monte Carlo simulators with the three valley model and the full band Monte Carlo model are used to explore electron transport in bulk wurtzite gallium nitride (GaN).Comparison of the results based on the two mode...The Monte Carlo simulators with the three valley model and the full band Monte Carlo model are used to explore electron transport in bulk wurtzite gallium nitride (GaN).Comparison of the results based on the two models is made.The results based on both models are basically the same at the lower field region,but exhibit some differences at the higher field region.The electron average energy exhibits obvious difference at the high field region between the two models.This difference further causes several other differences of GaN properties,such as the drift velocity versus field characteristics,the repopulation.Because of the complicated energy band structures at the high energy region for wurtzite GaN,the analytical band structures in the three valley model can not cover all properties of the band structures of wurtzite GaN,so the results based on the full band Monte Carlo model should be more exact.展开更多
Electronic structure and optical properties of the zinc-blende InxGa1-xNyAs1-y system are calculated from the first-principles. Some relative simulations are performed using CA-PZ form of local density approximation i...Electronic structure and optical properties of the zinc-blende InxGa1-xNyAs1-y system are calculated from the first-principles. Some relative simulations are performed using CA-PZ form of local density approximation in the framework of density functional theory. The supercell of intrinsic GaAs is calculated and optimized by using different methods, and the LDA-CA-PZ gives the most stable structure. The band gap of InzGa1-x As tends to decrease with the increasing In concentration. For the case of In0.0625Ga0.9375NyAs1-y, the band gap will show slight difference when N concentration is larger than 18. 75~. The optical transition of In dopant in GaAs exhibits a red shift, while it is a blue shift for the N dopant in InGaAs. Besides, dielectric function, reflectivity, refractive index and loss function in different doping model of InxGa1-xNyAs1-y are also discussed.展开更多
The power conversion efficiency for single-junction solar cells is limited by the Shockley-Quiesser limit.An effective approach to realize high efficiency is to develop multi-junction cells.These years have witnessed ...The power conversion efficiency for single-junction solar cells is limited by the Shockley-Quiesser limit.An effective approach to realize high efficiency is to develop multi-junction cells.These years have witnessed the rapid development of organic–inorganic perovskite solar cells.The excellent optoelectronic properties and tunable bandgaps of perovskite materials make them potential candidates for developing tandem solar cells,by combining with silicon,Cu(In,Ga)Se_(2)and organic solar cells.In this review,we present the recent progress of perovskite-based tandem solar cells,including perovskite/silicon,perovskite/perovskite,perovskite/Cu(In,Ga)Se_(2),and perovskite/organic cells.Finally,the challenges and opportunities for perovskite-based tandem solar cells are discussed.展开更多
文摘The Monte Carlo simulators with the three valley model and the full band Monte Carlo model are used to explore electron transport in bulk wurtzite gallium nitride (GaN).Comparison of the results based on the two models is made.The results based on both models are basically the same at the lower field region,but exhibit some differences at the higher field region.The electron average energy exhibits obvious difference at the high field region between the two models.This difference further causes several other differences of GaN properties,such as the drift velocity versus field characteristics,the repopulation.Because of the complicated energy band structures at the high energy region for wurtzite GaN,the analytical band structures in the three valley model can not cover all properties of the band structures of wurtzite GaN,so the results based on the full band Monte Carlo model should be more exact.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No.BUPT2009RC0412the National Natural Science Foundation of China under Grant Nos.60908028 and 60971068
文摘Electronic structure and optical properties of the zinc-blende InxGa1-xNyAs1-y system are calculated from the first-principles. Some relative simulations are performed using CA-PZ form of local density approximation in the framework of density functional theory. The supercell of intrinsic GaAs is calculated and optimized by using different methods, and the LDA-CA-PZ gives the most stable structure. The band gap of InzGa1-x As tends to decrease with the increasing In concentration. For the case of In0.0625Ga0.9375NyAs1-y, the band gap will show slight difference when N concentration is larger than 18. 75~. The optical transition of In dopant in GaAs exhibits a red shift, while it is a blue shift for the N dopant in InGaAs. Besides, dielectric function, reflectivity, refractive index and loss function in different doping model of InxGa1-xNyAs1-y are also discussed.
基金the National Natural Science Foundation of China(51773045,21772030,51922032,and 21961160720)for financial support。
文摘The power conversion efficiency for single-junction solar cells is limited by the Shockley-Quiesser limit.An effective approach to realize high efficiency is to develop multi-junction cells.These years have witnessed the rapid development of organic–inorganic perovskite solar cells.The excellent optoelectronic properties and tunable bandgaps of perovskite materials make them potential candidates for developing tandem solar cells,by combining with silicon,Cu(In,Ga)Se_(2)and organic solar cells.In this review,we present the recent progress of perovskite-based tandem solar cells,including perovskite/silicon,perovskite/perovskite,perovskite/Cu(In,Ga)Se_(2),and perovskite/organic cells.Finally,the challenges and opportunities for perovskite-based tandem solar cells are discussed.
