Band gaps and band offsets in strained GaAs1−ySby on InP grown by metalorganic chemical vapor deposition

Metastable GaAs1−ySby with 0.22<y<0.70 has been grown pseudomorphically strained on (001) InP substrates using metalorganic chemical vapor deposition. The Sb concentration and layer thicknesses, ranging from 24 to 136 nm, were determined by high resolution x-ray diffraction (HRXRD) measurements. Low-temperature photoluminescence (PL) spectroscopy revealed spatially indirect band-to-band emission of electrons localized in the InP and holes in the GaAs1−ySby. At increased excitation power densities samples with layer thicknesses above 65 nm showed, also, spatially direct PL across the band gap of the strained GaAs1−ySby. From the PL data the band gap energy and the band offsets of GaAs1–ySby relative to InP were derived and compared with the predictions of the Model Solid Theory.