High Quality GaAs on Si Substrate by Epitaxial Lift-off Using SeS₂ and its Application to Devices

Abstract

A new method of chemical bonding for GaAs on Si has been developed using SeS₂. The bonding between GaAs and Si is very robust and withstands many processing steps. Using the epitaxial lift off (ELO) technique the thin film of GaAs is grafted to Si substrate. The film bonded by this method has longer minority carrier lifetime than heteroepitaxial GaAs film on Si. The current-voltage(I-V)characteristics of p-GaAs/n-Si, n-GaAs/n-Si, p-GaAs/p-Si and n-GaAs/p-Si were measured at room temperature. The I-V curve did not show a rectifying behavior when GaAs was bonded to Si with SeS₂ because of the formation of a high-resistance layer at the interface. The characteristics were greatly improved bsuby small additions of Sn to SeS₂ during the bonding process. The very low resistance is obtained with adding Sn in SeS₂ during the bonding. The properties of solar cells using this method were compared with those grown on Si substrate by heteroepitaxy and GaAs substrate.