Using the Debye model and existing experimental data of the pyroelectric coefficient of AlN, the temperature dependence of the pyroelectric coefficient as well as the spontaneous polarization of AlN is calculated over a wide temperature range from 0to1000K. The pyroelectric coefficient is proportional to T3 at low temperature and increases acutely from 0 to around 400K, and then increases gently from 400to1000K. It makes AlN uniquely suitable for application in high temperature pyroelectric sensors. The spontaneous polarization of AlN changes a little from 0to1000K, which indicates that the features of III-nitrides based devices will hardly be degraded by the change of the spontaneous polarization.

Determining the spontaneous polarization is a fundamental problem in the III-nitride field. However the experimental value of the spontaneous polarization has not yet been reported. In this study, a thermodynamic model is proposed to investigate the spontaneous polarization of GaN from the GaN high-pressure phase transition. Total macroscopic polarization is directly expressed as coefficients in expansion, and these coefficients are found to be conducted in experiments. The experimental value of the spontaneous polarization of GaN is estimated to be around −0.022 C/m2.

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Erratum: "Microstructure and dislocation of epitaxial InN films revealed by high resolution x-ray diffraction" †J.