Low Surface Roughness GaAs/Si Thin-Film Deposition Using Three-Step Growth Method in MBE

Epitaxial GaAs-on-Si is an ideal material system for studying the physics of mismatched heteroepitaxy of a polar semiconductor layer grown on a non-polar substrate like silicon. Understanding and optimization of the initial nucleation of GaAs on silicon is the most crucial step in the success of GaAs/Si heteroepitaxy. Molecular beam epitaxy (MBE) technique has been used to deposit hetero-epitaxial GaAs thin-film on off-angle Si (100) substrate using the three-step growth method. After optimizing the growth parameters of low temperature (LT) buffer layer and high temperature (HT) epilayer, XRD analyses were performed. Characterization results of the GaAs (004) films which were not subjected to annealing, show a full-width half maximum (FWHM) of 760.1 arc sec and a root mean square (RMS) surface roughness of lower than 1 nm for a scanning area of 10 μm × 10 μm.