We have used low energy electron-excited nano-luminescence (LEEN) spectrosc
opy to obtain electronic band gap, confined state, and deep level trap info
rmation from GaN surfaces and buried interfaces on a nanometer scale. This
local spectroscopy provides information available only indirectly by other
electronic techniques. Using LEEN in combination with other surface science
methods, we have probed the localized electronic states at GaN free surfac
es, metal-CaN contacts, GaN/InGaN quantum wells, AlGaN/GaN pseudomorphic he
terostructures. and GaN/sapphire template layers, Their properties are sens
itive to the interface chemical composition, bonding, and atomic structure
and in turn to the specifics of the epitaxial growth. The results highlight
new methods for understanding and controlling electronic properties of GaN
interfaces and their future applications, (C) 2001 Elsevier Science B,V. A
ll rights reserved.