Threading dislocation lines within indium nitride versus gallium nitride: The implications of different dominant dislocation line charge screening mechanisms

Abstract

Within n-type gallium nitride, the threading dislocation line defect sites act to trap free electrons from the bulk of this semiconductor material, thereby reducing the overall free electron concentration. In contrast, within n-type indium nitride, the threading dislocation line defect sites donate electrons, thereby contributing to the large unintentional free electron concentration observed for this semiconductor. In the present work, using an elementary model for the energy levels associated with the threading dislocation line defect sites, some of the implications of the different electron acceptor/donor characteristics of the threading dislocation line defect sites within n-type gallium nitride are contrasted with those within n-type indium nitride. Fundamentally different dominant screening mechanisms are found for the different materials, the screening within n-type gallium nitride being provided by the bulk ionized donors, the screening within n-type indium nitride being provided by the free carrier screening. We also explicitly derive and contrast the occupation statistics of the threading dislocation line defect sites within these two semiconductor materials.