Effect of stress and free-carrier concentration on photoluminescence in InN

Abstract

We report photoluminescence (PL) studies of InN epilayers grown by plasma-assisted molecular beam epitaxy with free-electron concentration ranging from 5.9×1017to4.2×1018cm−3. X-ray diffraction measurements are used to determine strains, which are best described as a combination of hydrostatic and biaxial. The PL energy is affected by both strains along with free-carrier concentration through band filling. PL spectra are used to estimate the dependence of the Fermi level on free-carrier concentration, taking strain into account. The fundamental energy gap is found to be ∼0.70eV. PL broadening is well described based on band filling.