High mobility in n-type GaN substrates.

High peak electron mobilities were observed in freestanding c-plane GaN layers. Two well-defined electrical layers, a low mobility degenerate interface layer, and a high mobility nondegenerate bulk layer, were present in these samples. The carrier concentrations and mobilities for the layers were extracted using two methods: (1) magnetic field dependent Hall effect analysis; and (2) a simple two layer Hall model with the assumption that one of the layers is degenerate. The electron Hall mobility of the bulk layer is found to peak at nearly 8000 cm2/V s at low temperature using the magnetic field dependent Hall effect analysis. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]