Structural and electronic properties of boron nitride thin films containing silicon

The incorporation of silicon into boron nitride films (BN:Si) has been achi eved during ion beam assisted deposition growth. A gradual change from cubi c boron nitride (c-BN) to hexagonal boron nitride (h-BN) was observed with increasing silicon concentration. Ultraviolet photoelectron spectroscopy, f ield emission, and field emission electron energy distribution experiments indicated that the observed electron transport and emission were due to hop ping conduction between localized states in a band at the Fermi level for t he undoped c-BN films and at the band tails of the valence band maximum for the BN:Si films. A negative electron affinity was observed for undoped c-B N films; this phenomenon disappeared upon silicon doping due to the transfo rmation to h-BN. No shift of the Fermi level was observed in any BN:Si film : thus, n-type doping can be excluded. (C) 1998 American Institute of Physi cs. [S0021-8979(98)03421-5].