Relief of thermal stress in heteroepitaxial GaAs on Si by mesa release and deposition

We demonstrate a mesa release and deposition (MRD) technology to realize stress relief in GaAs layers on Si, useful in practical device applications. A thin AlAs layer is incorporated in the heteroepitaxial GaAs layer about 1 μm from the GaAs/Si interface. Mesas are etched down to the AlAs release layer and subsequently underetched in a 5% HF solution at room temperature. Photoresist clamps keep the mesas in their exact position during the underetch process which results in a self‐aligned redeposition on the substrate after resist removal. We used spatially resolved photoluminescence on 100×200 μm2 GaAs‐on‐Si mesas before and after the MRD process to demonstrate the stress relief. Uniform stress relief is found and the residual strain observed in the photoluminescence spectra at 77 K (0.05±0.02%) is attributed to strain thermally induced upon cooling from 300 to 77 K.