Seminars Archive
Leonard J. Brillson
Abstract
Thursday, March 30, 2000, 11:30
Seminar Room, ground floor, Building "T"
Sincrotrone Trieste, Basovizza
I.D. required for external visitors
Low Energy Electron Excited Nano-Luminescence Spectroscopy of GaN surfaces
and interfaces
Leonard J. Brillson
(The Ohio State University)
ABSTRACT
Thin films only a few nanometers thick are integral to a growing array
of electronically -active structures, including quantum wells, pseudomorphic
heterojunctions with two-dimensional electron gas (2DEG) layers, and ultrathin
film passivation layers. Their electronic properties are especially important
for GaN and other III-nitride interfaces, where efficient charge transport
and large confined carrier concentrations enable high frequency and power
applications in thin films only a few nanometers thick. We have used low
energy electron excited nano-luminescence (LEEN) spectroscopy to obtain
electronic band gap, confined state, and deep level trap information 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 surfaces,
metal-GaN contacts, GaN/InGaN quantum wells, and AlGaN/GaN pseudomorphic
heterostructures. These studies reveal the sensitivity of GaN localized
states to the chemical composition and bonding near interfaces and in turn
to the specifics of the epitaxial growth, thereby highlighting new methods
to understand and control the electronic properties of the interface.
