Moments of phonon density of states spectra and characteristic phonon temperatures of wide band gap materials

We have re‐digitized a variety of phonon density of states (PDOS) spectra, that have been published by different researchers for the wide band gap materials diamond, SiC, BN, AlN, GaN, ZnO, ZnS, and ZnSe, including calculations of the respective first‐ and second‐order moments. Notwithstanding the obvious differences in concrete shapes of spectra presented for one and the same material by different authors, the respective magnitudes of estimated moments have been found in most cases to be nearly the same (to within uncertainties of some few%). Anticipated differences between phonon temperatures, Θ eff , that are effective in controlling the observable temperature dependences of fundamental energy gaps and the respective average phonon temperatures, Θ P , are seen to be throughout smaller than ±10%. The estimated high‐temperature limits of Debye temperatures, Θ D (∞), are found to be significantly higher (by factors of order 1.4) than Θ P . As a remarkable heuristic finding revealed by our numerical and analytical studies we can further state that, for SiC, AlN, GaN, ZnO, ZnS, and ZnSe, the individual Θ D (∞) values are nearly equal (within ±5%) to the respective average optical (LO/TO) phonon temperatures pertaining to the upper sections of the corresponding PDOS spectra. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)