Effects on the Surface and Luminescence Properties of GaAs by SF6 Plasma Passivation

Yumeng Xu,Baoxue Bo,Lu Zhou,Xin Gao,Zhongliang Qiao,Jing Zhang,Xiaolei Zhang

doi:10.3390/cryst8090339

Yumeng Xu, Baoxue Bo + Show 5 more

Open Access

https://doi.org/10.3390/cryst8090339

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Abstract

The passivation effects of the SF6 plasma on a GaAs surface has been investigated by using the radio frequency (RF) plasma method. The RF’s power, chamber pressure, and plasma treatment time are optimized by photoluminescence (PL), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The PL intensity of passivated GaAs samples is about 1.8 times higher than those which are untreated. The oxide traps and As-As dimers can be removed effectively by using SF6 plasma treatment, and Ga-F can form on the surface of GaAs. It has also been found that the stability of the passivated GaAs surface can be enhanced by depositing SiO2 films onto the GaAs surface. These indicate that the passivation of GaAs surfaces can be achieved by using SF6 plasma treatment.

Highlights

GaAs is a kind of typical III-V group of semiconductor materials with a large direct band gap, high carrier mobility, and superior thermal stability, which is widely used for the fabrication of semiconductor lasers, solar batteries, ultraviolet photodetectors, etc
The traditional passivation for GaAs is mainly based on wet passivation by sulfur-containing solutions [4,5,6,7], which can form a thin layer of sulfide to saturate part of the dangling bonds, and to remove native oxides on GaAs surfaces effectively
Fluorine-based plasma is reported to be another good way for passivating the GaAs surface, because it is capable of passivating the oxygen vacancies by CF4 [9,10] and SF6 [11,12,13,14]

Summary

Introduction

GaAs is a kind of typical III-V group of semiconductor materials with a large direct band gap, high carrier mobility, and superior thermal stability, which is widely used for the fabrication of semiconductor lasers, solar batteries, ultraviolet photodetectors, etc. The traditional passivation for GaAs is mainly based on wet passivation by sulfur-containing solutions [4,5,6,7], which can form a thin layer of sulfide to saturate part of the dangling bonds, and to remove native oxides on GaAs surfaces effectively. This passivation method can reduce the surface nonradiative recombination, the thin sulfur passivation layer is not stable in an atmospheric environment and the passivation effect will obviously degrade in a short period of time. The passivation effect by SF6 plasma under different RF powers, chamber pressures, and plasma treatment times has been studied in detail by PL, AFM, and XPS measurements

Experiment

Background vacuum

RF Power Effect

Chamber Pressure Effect

Plasma

Figures show of Sby

4.4.Conclusions