Built-in-polarization and thermal conductivity of InxGa1-xN/GaN heterostructures

The effect of built-in-polarization (BIP) field on thermal properties of InxGa1−xN/GaN heterostructure has been investigated. The thermal conductivity k of InxGa1−xN alloy has been estimated using Callaway's formula including the BIP field for In content x = 0, 0.1, 0.3, 0.5 and 0.9. This study reports that irrespective of In content, the room temperature k of InxGa1−xN/GaN heterostructure is enhanced by BIP field. The result predicts the existence of a characteristic temperature Tp at which both thermal conductivities (including and excluding BIP field) show a crossover. This gives signature of pyroelectric nature of InxGa1−xN alloy which arises due to variation of polarization with temperature indicating that thermal conductivity measurement can reveal pyroelectric nature. The pyroelectric transition temperature of InxGa1−xN alloy has been predicted for various x. The composition dependent nature of room temperature k for x = 0.1 and 0.5 are in line with prior experimental studies. The result can be used to minimize the self heating effect in InxGa1−xN/GaN heterostructures.