Technology development for the growth of semi-insulating bulk GaN and investigation of in-situ carbon doping

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Nitride semiconductor research is presently one of the most challenging topics in the field of advanced electronics and optoelectronics. The proposed research program is motivated by the present lack of high-quality and inexpensive semi-insulating (SI) GaN substrates for all nitride-based electronic devices. It will focus on developing a novel GaN technology based on pseudohalide vapour phase transport (PVPE) for a significant improvement of the structural perfection of SI bulk crystals in comparison to Fe-doped HVPE-grown material. The 'pseudohalide' stands for a carbon-based transport of Ga and a subsequent reaction with ammonia to form GaN, utilizing a self-organized carbon mask to reduce the dislocation density at initial stages of growth, while keeping the carbon content below the solubility limit in subsequent GaN bulk growth. Control of carbon incorporation is provided by introduction of carbon-containing gas in a growth chamber free from graphite materials. The grown bulk GaN of high crystalline perfection will be carbon-doped which provides for SI properties. The electrical properties of the bulk GaN will be explored and controlled. Fundamental studies of the compensation mechanisms arising from carbon doping will be performed by applying state-of-the-art characterization methods.