Critical point transitions of wurtzite indium nitride

The optical transmission, photoluminescence, and reflection spectra have been measured on a high-quality wurtzite indium nitride (InN) single crystal in the range of 0.5-20.0 eV. The fundamental bandgap of intrinsic InN has been extracted by taking into account the Burstein-Moss shift, bandgap renormalization and Urbach band tail effects, and found to be very close to the recent strongly re-established value of ∼1.2 eV. With the aid of Adachi's dielectric function model for the vacuum ultraviolet reflection spectra and the empirical pseudopotential method approach for the electron band-structure, we are able to identify up to nine electronic transitions, showing clear picture for the critical point transitions in InN. The temperature dependence of these interband transitions has also been revealed.