Properties of Zn-doped VPE-grown GaN. II. Optical cross sections

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Abstract
Experimental data are presented for optical cross sections σ0n(hν) related to the four deep acceptorlike Zn‐related radiative levels A–D in GaN. Very accurate spectral data were obtained by the photoluminescence excitation (PLE) technique, at temperatures varying from 4.2 up to 293 K. From a detailed comparison of the spectral behavior of the emission and absorption spectra, the size of electronic broadening effects could be determined in the overlap region. The binding energies for Zn‐related acceptor levels were obtained as EA=0.34±0.04, EB=0.65±0.08, EC=1.02±0.05, and ED=1.42±0.08 eV at low temperature. Optical transmission data give estimates of absolute values for optical cross sections at saturation, varying from σ0nA(sat) ?1×10−16 to σnD(sat) ?5×10−18 cm2. Temperature broadening effects in optical cross sections are well explained by a linear model for phonon coupling in the optical transitions, employing the same phonon energies and coupling strengths as were evaluated from emission spectra.