Growth of GaN on Si(111): Surfaces and crystallinity of the epifilms and the transport behavior of GaNSi heterojunctions

Growths of GaN on Si(111)- (7 × 7) substrates by plasma-assisted molecular-beam epitaxy (PA-MBE) have been studied. Optimal conditions of MBE and the effect of a lowerature (LT) buffer are followed. It is found that irrespective of the growth conditions and the growth strategies (direct versus two-step growth), a thin amorphous-like interface layer always forms. For smooth surfaces and better crystallinity of the epifilms, a LT-buffer preceding the higherature deposition is helpful, and the grown GaN films are of nitrogen-polar. Transport measurements of the heterojunctions of GaN on heavily p- and n-doped Si reveal ohmic behavior, whereas that of n-GaN on lightly doped n--Si substrate shows rectifying characteristics. © 2011 American Institute of Physics