Effect of SiO₂ Nano-Interlayer to Characteristics of GaAs/Ge Heterostructure

Abstract

This work investigates the effect of a SiO2 nano-interlayer to optoelectronic characteristics of GaAs/Ge heterostructures. The experimental focuses on three parts: first of all, studying crystal quality of GaAs and GaAs/SiO2 films on Ge substrates prepared by RF magnetron sputtering. Next, it studies the effect of the SiO2 nano-interlayer with different thickness to the properties of the device structure by using the results of the optoelectronic characteristics of the GaAs/Ge and GaAs/ SiO2/Ge heterostructures. Third, we investigate the optoelectronic characteristics of the GaAs/ SiO2/Ge structure In the GaAs/SiO2/Ge heterostructure, except for the diffraction peak of GaAs layer at around 53˚, a strong peak at 52˚ responding to be gallium oxide (Ga2O3) was observed. That is the reaction product of oxygen (O2) and gallium (Ga) from the SiO2 layer. The diffraction peak intensity of GaAs decreases and the diffraction peak intensity of Ga2O3 increases as the deposition time increases. This may contributed to the arsenic native point defect caused by the introduction of oxygen from the SiO2 layer and then to form Ga2O3. Under illumination, the arsenic native point defect in the GaAs layer will capture photo-generated electrons, resulting photocurrent decrease, thereby affecting the optical properties of GaAs/SiO2/Ge heterostructures.