High mobility in n-type GaN substrates

High peak electron mobilities were observed in freestanding c-plane GaN lay ers. Two well-defined electrical layers, a low mobility degenerate interfac e layer, and a high mobility nondegenerate bulk layer, were present in thes e samples. The carrier concentrations and mobilities for the layers were ex tracted using two methods: (1) magnetic field dependent Hall effect analysi s; and (2) a simple two layer Hall model with the assumption that one of th e layers is degenerate. The electron Hall mobility of the bulk layer is fou nd to peak at nearly 8000 cm(2)/V s at low temperature using the magnetic f ield dependent Hall effect analysis. (C) 2001 American Institute of Physics .