Efficient P-Type Doping and the Role of Defects in Limiting Acceptor Activation in III-Nitrides

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The objective of this research is obtaining highly conductive p-type layers in gallim nitride (GaN). The approach for accomplishing this objective is identifying defects limiting the p-type conduction in GaN and then reducing the density of these defects by using a novel ultra high-speed microwave annealing technique. Intellectual Merit: The defects and the defect complexes responsible for acceptor levels and several unidentified self-compensating deep donor levels in p-type in-situ and ion-implantation doped GaN epilayers will be investigated by performing photoluminescence, cathodoluminescence, Hall and secondary-ion-mass-spectrometry measurements on undoped and acceptor doped GaN layers prepared under several controlling conditions. Acceptor doped materials that will be studied in this work include both in-situ doped epilayers and post-growth ion-implantation doped layers. The in-situ and ion-implantation doped nitride layers will be subjected to a new ultra-fast high-temperature (1400C) microwave annealing step to repair the implant damage and to quench the native defects, which may be affecting the acceptor activation in both in-situ and ion-implantation doped layers. During annealing, the GaN layer will be protected by a graphite or an AlN cap. The intentionally introduced acceptor dopants will be Mg and Be. Broader Impact: Successful results of this work may have profound effect on the development of high-power, microwave, high-temperature and optoelectronic devices, which are of interest for national security. This work will be done in collaboration with several federal laboratories. Undergraduate and high-school students will be involved in the project. Results of the proposed work will be included in a special topics graduate course.