Temperature-dependent optical band gap of the metastable zinc-blende structure -GaN

The temperature-dependent (10300 K) optical band gap E0(T) of the epitaxial metastable zinc-blende-structure -GaN(001)4×1 has been determined by modulated photoreflectance and used to interpret low-temperature photoluminescence spectra. E0 in -GaN was found to vary from 3.3020.004 eV at 10 K to 3.2310.008 eV at 300 K with a temperature dependence given by E0(T) =3.3026.697×10-4T2/(T%2b600) eV. The spin-orbit splitting 0 in the valence band was determined to be 171 meV. The oscillations in the photoreflectance spectra were very sharp with a broadening parameter of only 10 meV at 10 K. The dominant transition observed in temperature-dependent photoluminescence was attributed to radiative recombination between a shallow donor, at 11 meV below the conduction-band edge and the valence band. © 1994 The American Physical Society.

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