Heterojunction Diodes and Solar Cells Fabricated by Sputtering of GaAs on Single Crystalline Si

Abstract

This work reports fabrication details of heterojunction diodes and solar cells obtained by sputter deposition of amorphous GaAs on p-doped single crystalline Si. The effects of two additional process steps were investigated: A hydrofluoric acid (HF) etching treatment of the Si substrate prior to the GaAs sputter deposition and a subsequent annealing treatment of the complete layered system. A transmission electron microscopy (TEM) exploration of the interface reveals the formation of a few nanometer thick SiO2 interface layer and some crystallinity degree of the GaAs layer close to the interface. It was shown that an additional HF etching treatment of the Si substrate improves the short circuit current and degrades the open circuit voltage of the solar cells. Furthermore, an additional thermal annealing step was performed on some selected samples before and after the deposition of an indium tin oxide (ITO) film on top of the a-GaAs layer. It was found that the occurrence of surface related defects is reduced in case of a heat treatment performed after the deposition of the ITO layer, which also results in a reduction of the dark saturation current density and resistive losses.

An Investigation of The J-V Curve for N-AlGaAs/p-GaAs Heterojunction Solar Cell Due to Influence of Surface Recombination Velocity

“…Various heterojunctions, including Si-GaAs, Si-GaP, GaAs-Ge and other such materials have been used for making solar cells [1][2][3]. Gallium arsenide (GaAs) is an excellent semiconductor for the fabrication of high efficient solar cell due to its high absorption of light and has an ideal band gap for solar photovoltaic conversion.…”

GaAs/Ge/Si epitaxial substrates: Development and characteristics

“…Such a replacement is also a necessary step towards the monolithic integration of III-V-based optoelectronic devices and Si chips. [1][2][3][4] Despite the urgency of this issue and multiple years of research aimed at solving this problem, no significant success has been achieved in this field so far. 1 This is due to a number of fundamental problems, the most important of which are an appreciable mismatch of the lattice parameters and thermal expansion coefficients of Si and GaAs, as well as the growth peculiarities of a polar GaAs layer on a nonpolar Si substrate.…”