As Grown Stress Free GaAs on Si by Regrowth on Chemically Released GaAs on Si Mesas

GaAs layers are grown on GaAs on Si mesas, fabricated using a novel Mesa Release and Deposition (MRD) technique. The mesas that serve as the substrate for selective epitaxy are fabricated in a 1 µm thick GaAs on Si layer. The MRD structures are obtained after a complete underetching of the mesas and subsequent deposition, self-aligned on their original positions. The samples carrying the MRD structures are cleaned before epitaxy and a GaAs epilayer is deposited. Spatialy resolved photoluminescence is used to assess the strain level in the regrown layer. In contrast to the expected shift and splitting of the valence band of biaxially strained GaAs/Si, we find that the peak shift of the band-to-band optical transition of the heteroepitaxial GaAs/MRD/Si to the GaAs reference at 77 K is only 4 nm and no valence band splitting is observed for the regrown layer.