Red-green luminescence in indium gallium nitride alloys investigated by high pressure optical spectroscopy

We performed optical absorption and photoluminescence experiments under high pressure up to 10 GPa on two good quality InGaN epilayers with ∼40% indium. The pressure coefficient of about 30 meV/GPa for the absorption edge is close to the bandgap pressure coefficients of InN and GaN, indicating similar pressure dependence of the fundamental band gap in the whole composition range. In contrast, the pressure coefficient of the photoluminescence peak energy shows much weaker pressure dependence which we attribute to an increasing role of highly localized defects when the conduction band approaches the Fermi level stabilization energy at higher indium contents. © 2012 American Institute of Physics.