Composition dependence of polarization fields in GaInN/GaN quantum wells

We report an experimental determination of the internal polarization field in GaInN/GaN quantum wells, due to piezoelectric and spontaneous polarization, utilizing the quantum confined Stark effect, with fields as large as 3.1 MV/cm at 22% In. From its dependence on quantum well composition and strain, we find that the total field in GaInN is a linear combination of polarization charges from GaN and InN. The piezoelectric constants d31 for GaN and InN derived from our data are 1.05±0.05 pm/V and 3.7±0.5 pm/V, in fair agreement with theoretical data.