Understanding of impact of carbon doping on background carrier conduction in GaN* *Project partially supported by the National Key Research and Development Program of China (Grant No. 2017YFB0402800), the Key Research and Development Program of Guangdong Province, China (Grant No. 2020B010174003), the National Natural Science Foundation of China (Grant No. U1601210), and the Natural Science Foundation of Guangdong Province, China

Abstract

The impact of carbon doping on the background carrier conduction in GaN has been investigated. It is found that the incorporation of carbon can effectively suppress the n-type background carrier concentration as expected. Moreover, from the fitting of the temperature-dependent carrier concentration and mobility, it is observed that high nitrogen–vacancy (VN) dominates the background carrier at room temperature which consequently results in n-type conduction. The doping agent (carbon atom) occupies the nitrogen site of GaN and forms CN deep acceptor as revealed from photoluminescence. Besides, a relatively low hole concentration is ionized at room temperature which was insufficient for the compensation of n-type background carriers. Therefore, we concluded that this background carrier concentration can be suppressed by carbon doping, which substitutes the N site of GaN and finally decreases the VN.