Composition and optical properties of dilute-Sb GaN1-xSbx highly mismatched alloys grown by MBE

In this work the compositional and optical characterization of three series of dilute-Sb GaN_1-xSb_x alloys grown with various Sb flux, under N and Ga-rich conditions, are presented. Using wavelength dispersive x-ray microanalysis and Rutherford backscattering spectroscopy it is found that the N-rich samples (Ga flux <2.3 × 10^-7 Torr) incorporate a higher magnitude of GaSb than the Ga-rich samples (Ga flux > 2.3 × 10^-7 Torr) under the same growth conditions. The optical properties of the Ga-rich samples are measured using room temperature cathodoluminescence (CL), photoluminescence (PL) and absorption measurements. A broad luminescence peak is observed around 2.2 eV. The nature and properties of this peak are considered, as is the suitability of these dilute-Sb alloys for use in solar energy conversion devices.