Highly mismatched N-rich GaN1−xSbx films grown by low temperature molecular beam epitaxy

We have grown N-rich, dilute Sb GaN1−xSbx alloys by low temperature molecular beam epitaxy. At low growth temperature of <100 °C the material loses crystallinity and becomes primarily amorphous with small crystallites of 2–5 nm at a Sb composition of >4 at. %. Despite the different microstructures found for GaN1−xSbx alloys with different composition, the absorption edge shifts continuously from 3.4 eV (GaN) to close to 1 eV for samples with Sb content >30 at. %. GaN1−xSbx alloys with less than 5 at. % Sb show sufficient bandgap reduction (∼2 eV), making them suitable for photoelectrochemical applications.