GaN room temperature exciton spectra by photovoltaic measurement

Abstract

Exciton absorption peak has been clearly observed at room temperature by photovoltaic spectra, on a GaN layer grown on (0001)-plane Sapphire by metallorganic chemical vapor deposition. From the spectra, we obtained A and B exciton transition energies to be 3.401 eV, 3.408 eV, and the energy gap to be 3.426 eV in wurztite GaN, respectively. We have also performed photovoltaic measurements with various incidence angles of light, and observed the polarization behavior of exciton absorption in GaN. Finally, we used UV-polarizer to further confirm the polarization properties of GaN. In conjunction with previous room temperature photoreflectance measurements, this work provide direct and reliable assessment of the excitonic properties and crystal quality of GaN semiconductor layers.