Small band gap bowing in In1−xGaxN alloys

Abstract

High-quality wurtzite-structured In-rich ${\mathrm{In}}_{\text{1−x}}{\mathrm{Ga}}_x\mathrm{N}$ films $\text{(0⩽x⩽0.5)}$ have been grown on sapphire substrates by molecular beam epitaxy. Their optical properties were characterized by optical absorption and photoluminescence spectroscopy. The investigation reveals that the narrow fundamental band gap for InN is near 0.8 eV and that the band gap increases with increasing Ga content. Combined with previously reported results on the Ga-rich side, the band gap versus composition plot for ${\mathrm{In}}_{\text{1−x}}{\mathrm{Ga}}_x\mathrm{N}$ alloys is well fit with a bowing parameter of ∼1.4 eV. The direct band gap of the ${\mathrm{In}}_{\text{1−x}}{\mathrm{Ga}}_x\mathrm{N}$ system covers a very broad spectral region ranging from near-infrared to near-ultraviolet.