Tensile stress variations of chemically etched GaAs films grown on Si substrates

Photoluminescence (PL) at 77 K is used to study tensile stress variations in chemically etched stripes of a 3-μm-thick GaAs film grown on Si substrate. The etched patterns consist of 1-mm-long stripes with widths ranging from 100 to 4 μm and 4 μm by 4 μm squares. We observed monotonic shift of PL peaks towards shorter wavelength for decreasing stripe width. In particular, when the width of the stripe is less than 7 μm, tensile stress is essentially uniaxial as evident from the magnitude of shift in PL peaks. The polarization characteristics of the PL spectra of these uniaxially stressed stripes are investigated and found to agree well with theoretical predictions.