Identifying Defects and their Electronic Signatures in Regrown GaN Heterostructures

Although silicon-based electronics are used to power light-emitting diodes and electric vehicles, their utility in high power applications is limited by a low breakdown voltage. The most promising alternative power devices consist of vertical GaN devices, which often require regrown active regions. Thus, advances in high power device performance require a detailed understanding of the influence of regrowth processing steps on interfacial defects and their electronic signatures. In this work, we examine a series of GaN p-i-n structures prepared with and without ex-situ ambient exposure and/or chemical etching. To quantify the concentration of various native and extrinsic point defects, we utilize a combination of ion beam analyses in conjunction with x-ray diffraction. For all samples, channeling Rutherford backscattering spectroscopy data reveals minimum yield values < 2%, with displaced atom densities ranging from 1 to 3 x 10²⁰/cm³. For all samples, cathodoluminescence spectroscopy reveals the GaN near-bandedge and donor-acceptor pair luminescence. We discuss the influence of interface regrowth on variations in the density of displaced Ga atoms and the intensity of yellow and infrared luminescence.