Abstract
The band to band tunneling of defective GaAs nano-junction is studied by using the non-equilibrium Green’s function formalism with density functional theory. Aiming at performance improvement, two types of defect-induced transport behaviors are reported in this work. By examining the partial density of states of the system, we find the substitutional defect OAs that locates in the middle of tunneling region will introduce band-gap states, which can be used as stepping stones to increase the tunneling current nearly 3 times higher at large bias voltage (Vb≥0.3V). Another type of defects SeAs and VGa (Ga vacancy) create donor and acceptor states at the edge of conduction band (CB) and valence band (VB)respectively, which can change the band bending of the junction as well as increase the tunneling field obtaining a 1.5 times higher ON current. This provides an effective defect engineering approach for next generation TFET device design.
Highlights
Oxygen is a common impurity in many semiconductor materials and most experimental interests have been directed toward O substituting for As (OAs).[21,22]
The calculations of defect feature in a GaAs bulk or tunnel junction were carried out by using first-principle calculation software package Atomistic ToolKit based on the density functional theory (DFT) in combination with the non-equilibrium Green’s function.[29,30]
It is well known that compared with experimental values, the local density approximation (LDA) calculation exist the problem of underestimating the band gap value
Summary
Most of the studies on III-V semiconductor devices were focused on conventional metal-oxide-semiconductor field-effect transistor (MOSFET) structures.[1,2] Another intriguing possibility is using them to design band-to-band tunneling (BTBT) field-effect transistor (or tunnel field-effect transistors, TFET),[3] which can realize a larger on-off current ratio and smaller subthreshold swing (SS).[4,5,6,7] Recently, the GaAs-based devices in nanometer scale[8,9,10,11,12] are considered as one of the promising material candidates for future high-speed optoelectronic applications.[13,14,15] the relatively large band gap is a special challenge to enhance on-state currents for the TFET application. Ab initio simulation study of defect assisted Zener tunneling in GaAs diode Juan Lu,[1,2] Zhi-Qiang Fan,[2] Jian Gong,1,a and Xiang-Wei Jiang2,3,a 1School of Physics and Technology, Inner Mongolia University, Hohhot 010021, People’s Republic of China 2State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, People’s Republic of China 3Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China (Received 11 March 2017; accepted 29 May 2017; published online 6 June 2017)
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