Pyroelectric Property of Binary Nitrides (AlN, GaN and InN)

The pyroelectric (PY) property of binary nitrides (AlN, GaN and InN) has been explored theoretically. The spontaneous and piezoelectric (PZ) polarization modifies the thermal conductivity of these nitrides. The thermal conductivities as a function of temperature including and excluding the polarization mechanism (kp and k) predict a transition temperature (Tp) between primary and secondary PY effects. Below Tp, thermal conductivity kp is lower than k. This is due to negative thermal expansion in binary nitrides. Above Tp, kp is greater than k. kp is significantly contributed by PZ polarization due to thermal expansion which is the reason of secondary PY effect. The transition temperature Tp for AlN, GaN and InN has been predicted as 100 K, 70 K and 60 K, respectively. This study suggests that thermal conductivity study can reveal PY property in semiconductors.