Studies on Electrical and Thermal Transport of InN based on Two Layer Model

Abstract

InN, a material of huge potential in device applications, is grown on sapphire substrate. But due to the high lattice mismatch between the sapphire and InN, the large number of dislocations develops near the interface between the two materials. However, the density of threading dislocation falls sharply in the bulk layer. The charge density has also similar variation. Therefore, the bulk InN crystal may be treated to be consisting of two layers, one the interfacial layer where the density of dislocations is very high and the layer on the interfacial layer, called bulk layer which has much lower density of dislocation and is considered to be negligible. We have calculated the mobility of InN and Seebeck Coefficient of InN based on the two layer model. We find that the theoretical values of mobility based on two layer model matches quite well with the experimental data. In our model, in the interfacial layer, the dislocation scattering and ionized impurity scattering mechanisms are considered to be the dominating scattering mechanisms while for the bulk layer, the acoustic phonon scattering via deformation potential and piezo electric coupling, ionized impurity scattering and optical phonon scattering mechanisms are considered. The theoretical values of the thermoelectric power of InN, calculated on the basis of two layer model are found to be in good agreement with experimental data.
Keywords: Dislocations, two layer model, thermoelectric power, mobility