Band offset in semiconductors is a fundamental physical quantity that determines the performance of optoelectronic devices.However,the current method of calculating band offset is difficult to apply directly to the la...Band offset in semiconductors is a fundamental physical quantity that determines the performance of optoelectronic devices.However,the current method of calculating band offset is difficult to apply directly to the large-lattice-mismatched and heterovalent semiconductors because of the existing electric field and large strain at the interfaces.Here,we proposed a modified method to calculate band offsets for such systems,in which the core energy level shifts caused by heterovalent effects and lattice mismatch are estimated by interface reconstruction and the insertion of unidirectional strain structures as transitions,respectively.Taking the Si and III-V systems as examples,the results have the same accuracy as what is a widely used method for small-lattice-mismatched systems,and are much closer to the experimental values for the large-lattice-mismatched and heterovalent systems.Furthermore,by systematically studying the heterojunctions of Si and III-V semiconductors along different directions,it is found that the band offsets of Si/InAs and Si/InSb systems in[100],[110]and[111]directions belong to the type I,and could be beneficial for silicon-based luminescence performance.Our study offers a more reliable and direct method for calculating band offsets of large-lattice-mismatched and heterovalent semiconductors,and could provide theoretical support for the design of the high-performance silicon-based light sources.展开更多
The giant Stark effect(GSE) in a set of van der Waals(vdW) heterostructures is studied using first-principles methods. A straightforward model based on quasi-Fermi levels is proposed to describe the influence of an ex...The giant Stark effect(GSE) in a set of van der Waals(vdW) heterostructures is studied using first-principles methods. A straightforward model based on quasi-Fermi levels is proposed to describe the influence of an external perpendicular electric field on both band gap and band edges. Although a general linear GSE is observed, which is induced by the almost linear variation of the band edges of each layer in the heterostructures, when vdW heterostructures is subjected to small electric fields the variation becomes nonlinear. This can be attributed to the band offsets-induced interlayer charge transfer and resulted intraand inter-layer Coulomb interactions. Our work, thus offers new insight into the mechanism of the nonlinear GSE in vdW heterostructures, which is important for the applications of vdW heterostructures on nanoelectronic devices.展开更多
基金This work was supported by the National Key Research and Development Program of China(Grant No.2018YFB2200100)the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB22)+1 种基金the National Natural Science Foundation of China(Grant No.118764347,11614003,11804333)H.X.D.was also supported by the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2017154).
文摘Band offset in semiconductors is a fundamental physical quantity that determines the performance of optoelectronic devices.However,the current method of calculating band offset is difficult to apply directly to the large-lattice-mismatched and heterovalent semiconductors because of the existing electric field and large strain at the interfaces.Here,we proposed a modified method to calculate band offsets for such systems,in which the core energy level shifts caused by heterovalent effects and lattice mismatch are estimated by interface reconstruction and the insertion of unidirectional strain structures as transitions,respectively.Taking the Si and III-V systems as examples,the results have the same accuracy as what is a widely used method for small-lattice-mismatched systems,and are much closer to the experimental values for the large-lattice-mismatched and heterovalent systems.Furthermore,by systematically studying the heterojunctions of Si and III-V semiconductors along different directions,it is found that the band offsets of Si/InAs and Si/InSb systems in[100],[110]and[111]directions belong to the type I,and could be beneficial for silicon-based luminescence performance.Our study offers a more reliable and direct method for calculating band offsets of large-lattice-mismatched and heterovalent semiconductors,and could provide theoretical support for the design of the high-performance silicon-based light sources.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFB0700700)the National Natural Science Foundation of China(Grant Nos.61622406,11674310,61571415,61427901,51502283,and U1530401)
文摘The giant Stark effect(GSE) in a set of van der Waals(vdW) heterostructures is studied using first-principles methods. A straightforward model based on quasi-Fermi levels is proposed to describe the influence of an external perpendicular electric field on both band gap and band edges. Although a general linear GSE is observed, which is induced by the almost linear variation of the band edges of each layer in the heterostructures, when vdW heterostructures is subjected to small electric fields the variation becomes nonlinear. This can be attributed to the band offsets-induced interlayer charge transfer and resulted intraand inter-layer Coulomb interactions. Our work, thus offers new insight into the mechanism of the nonlinear GSE in vdW heterostructures, which is important for the applications of vdW heterostructures on nanoelectronic devices.
