Tuning performance: strain modulation of GaAs layers grown on meso-porous silicon substrates

A novel compliant substrate, comprising mono-layers (PS1, PS2) and multi-layers (PSML1, PSML2) of porous silicon structures, fabricated using galvanostatic mode, was employed for the Molecular Beam Epitaxy (MBE) growth of 0.5 µm GaAs. To counteract the lattice parameter mismatch, the growth process was tailored with a buffer layer SiGe, a gradual Si_1−xGe_x with and without an in-situ annealing. Our investigation primarily proposes a compliant substrate as a platform for GaAs growth, which can serve in photodiodes and lasers applications. Field-Emission Scanning Electron Microscopy (FE-SEM) and High-Resolution X-Ray Diffraction (HR-XRD) identified PS2 and PSML2 as potential candidates for further investigations. The Si_1−xGe_x buffer layer has mitigated the formation of the 3D GaAs hillocks in PS2. Although, this approach has led to the formation of "lamellar twins" in PSML2, as a consequence of the substantial stress excreted by high porosity layers (HPLs) stack during the growth process. This strain was confirmed by the redshift of the GaAs Photoluminescence (PL) peak. Energy dispersive Spectroscopy (EDS) and X-ray Photoelectron spectroscopy (XPS) demonstrated that the GaAs layer was in its pure state. An in-situ annealing at 680 °C, resulted in a respective decrease in the full width at half maximum (FWHM) of the HR-XRD rucking curves (658.68 arc s).