Dependence of the luminescence energy in InGaN quantum-well structures on applied biaxial strain

Direct application of biaxial strain to GaN and InGaN/GaN multiple quantum-well (MQW) structures is achieved through the use of a specially designed pressure cell. The photoluminescence of the samples is measured as a function of the applied biaxial strain. The luminescence of the GaN sample redshifts with tensile strain in a manner that agrees quantitatively with the expected shrinkage of the energy gap. The luminescence of the InGaN MQW structures shows a smaller than expected redshift for one sample, and a blueshift for another. This blueshift agrees with calculations based on the built-in electric field and the piezoelectric effect in a quantum well in which the radiative recombination is dominated by the quantum-confined Stark effect.