Influence of Surface Treatments on the Structure of GaN Layers

Although silicon-based electronics are used to power light-emitting diodes and electric vehicles, their utility in high power applications is limited by slow switching and high on-state resistance. The most promising alternatives are vertical GaN devices, but these require etching and selective-area re-growth that may displace surface and near-surface Ga and N atoms. To understand processing-structure-property relationships relevant to vertical GaN devices, we examine the influence of dry etching and metal-organic (MO) precursor treatment on the structure and properties of GaN substrates and epitaxial GaN layers. For these studies, we visualize the crystal symmetry/orientation using 2D planar ion channeling maps and angular yield profiles collected with a fully-automated 5-axis goniometer recently attached to the endstation of the 1.7 MeV Tandetron at the Michigan Ion Beam Laboratory. Our results suggest that the MO precursor reduces the density of displaced surface Ga atoms. To quantify the concentration and distribution of displaced atoms, we will compare 2D ion channeling maps with 2D Monte Carlo-Molecular Dynamics simulations using Flux 7.9.6. We will also present 2D maps of elastic recoil detection analysis spectra to evaluate the spatial distribution of H.