Growth and Optical Properties of InGaAs via Ge-Based Virtual Substrates: A New Chemistry Based Strategy

In this study, we report the epitaxial integration of InGaAs films on Ge/Si(100) virtual substrates for photonic applications. Ge buffer layers with thicknesses of 400-700 nm were grown directly on vicinal (5 degrees miscut) and on-axis Si (100) wafers using a new low-temperature, chemistry-based approach that allows unprecedented control of film microstructure, morphology and purity at CMOS-compatible conditions. In0.01Ga0.49As0.50 films lattice matched to Ge and with thicknesses in the range of 800-2500 nm were then deposited on both Ge/Si substrates and bulk Ge wafers using industrial MOCVD. All materials were characterized by high-resolution X-ray diffraction, atomic force microscopy, transmission electron microscopy, time-resolved and steady-state photoluminescence, as well as cathodoluminescence. It is found that the properties of the InGaAs/Ge/Si(100) samples are comparable with those grown directly on bulk Ge platforms. Most importantly the films grown on miscut Ge templates are devoid of deleterious antiphase boundaries, making them promising candidates for large scale production of III-V photovoltaics.