Various kinds of nitride semiconductor devices using a nitride semiconductor, such as gallium nitride, have been developed. Examples thereof include semiconductor light emitting devices, such as an ultraviolet, blue, or green light emitting diode (LED), and a purple-blue or blue laser diode (LD).
A GaN layer of the nitride semiconductor device is usually formed on a sapphire substrate or the like. However, due to a reduction in cost and an increase in diameter of a wafer, it is desirable to establish a technique for growing the GaN layer on a substrate other than the sapphire substrate.