关键词: GaAs纳米线/
表面钝化/
能带结构
English Abstract
Effect of surface passivation on the electronic properties of GaAs nanowire:A first-principle study
Zhang Yong1,Shi Yi-Min1,
Bao You-Zhen1,
Yu Xia1,
Xie Zhong-Xiang1,
Ning Feng2
1.School of Mathematics, Physics and Energy Engineering, Hunan Institute of Technology, Hengyang 421002, China;
2.College of Physics and Electronic Engineering, Guangxi Teachers Education University, Nanning 530001, China}
Fund Project:Project supported by the National Natural Science Foundation of China (Grant Nos. 11704112, 11547197, 61640405, 61704036), the Hunan Provincial Nature Science Foundation of China (Grant Nos. 2017JJ3051, 2017JJ2062), the Program of Hunan Provincial Education Department of China (Grant Nos. 17B066, 17B065, 16A052), by the Science and Technology Planning Project of Hengyang, China (Grant No. 2016KJ14), the Student Innovation Training Program of Hunan Institute of Technology, China (Grant No. HX1608), and the Program of Student Research and Innovation Experiment of Hunan, China.Received Date:14 May 2017
Accepted Date:04 July 2017
Published Online:05 October 2017
Abstract:Crystal structures of GaAs nanowires prepared by employing molecular beam epitaxy technique are often dominated by the wurtzite (WZ) phase.Recently,Galicka et al.found that the WZ GaAs nanowires grown along the[0001]direction in smaller size are energetically more favorable than other nanowires with the zinc blende phase grown along a specific direction (2008 J.Phys.:Condens.Matter 20 454226).The native nanowire usually has abundant unsaturated surface dangling bonds (SDBs) inducing significant surface states,leading to electrons accumulating at the nanowire surface. Thus the electrical property of the nanowire is very sensitive to the surface condition.However,surface passivation can effectively remove the surface states from the SDBs,and optimize the device performance.In this paper,using the first-principle calculations in combination with density function theory,we investigate the effect of surface passivation on the electronic structure of the GaAs nanowires grown along the[0001]direction.Various passivation species (hydrogen (H),fluorine (F),chlorine (Cl) and bromine (Br)) with different coverage ratios are considered.The GaAs nanowires hydrogenated with different locations and coverage ratios display different electronic properties.It is found that the GaAs native nanowire with a smaller diameter shows a semiconductor characteristic with indirect band gap,which originates from the fact that at smaller diameter,the surface stress becomes more remarkable,and then leads to surface atomic reconstruction.After passivation,the indirect band gap is translated into the direct band gap.For the GaAs nanowire with an As SDB hydrogenated,one deep donor level is located in the gap,and its band structure shows an n-type characteristic.For the GaAs nanowire with a Ga SDB hydrogenated,one shallow acceptor level is located in the gap,and its band structure shows a p-type characteristic.For the GaAs nanowire with a Ga-As dimer hydrogenated, its band structure shows an intrinsic semiconductor characteristic.For the GaAs nanowire with all of the Ga SDBs hydrogenated,the band structure shows a metallic characteristic.The band gap of the GaAs nanowire gradually increases as the hydrogen passivation ratio increases.For 50% hydrogen passivation,the band gap for the symmetrical passivation is slightly bigger than that for the half-side passivation.For the F-,Cl-and Br-passivation,the band gap decreases compared with for H-passivation.This is due to the fact that the ability of passivating atoms to compensate for surface atoms is weak,thereby reducing the band gap.The mechanism for the surface passivation is the suppression of surface states by the ability of the passivating atoms to compensate for surface atoms.These results show that the electronic properties of GaAs nanowires can be modulated by surface passivation,which is helpful for using GaAs nanowires as components and interconnections of nanoscale devices.
Keywords: GaAs nanowire/
surface passivation/
energy band structure
