X-ray diffraction studies of GaN p-i-n structures for high power electronics

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. In this work, we examine the p-i interface of a series of GaN p-i-n structures prepared with and without ex-situ ambient exposure and/or chemical etching. For the “in-situ” GaN structure, elastic recoil detection analysis (ERDA) revealed the highest interfacial [H] and Rutherford backscattering shows the highest density of displaced Ga atoms, likely due to efficient incorporation of Mg_Ga. Here, we report on x-ray diffraction studies of the crystallinity of the GaN p-i-n structures. The full width at half max (FWHM) of phi and omega scans were used to quantify the mosaicity and threading dislocation (TD) densities at the p-i interfaces. Interestingly, the lowest screw-type dislocation density and highest edge-type dislocation density are observed for the “in-situ” GaN structure. The relationship between interfacial [H], displaced Ga, and screw- and edge-type dislocations will be discussed.