Seminars Archive
Angela Rizzi
Abstract
Wednesday, May 10, 2000, 14:30
Seminar Room, ground floor, Building "T"
Sincrotrone Trieste, Basovizza
I.D. required for external visitors
Group III-N wurtzite Heterostructures: Polarization Fields and their strong
Influence on the Electronic Properties
Angela Rizzi
(Universit di Modena & Forschungszentrum Jlich,
Germany)
ABSTRACT
Several effects characterize wurtzite III-N heterostructures as compared
with the classical zincblende III-V ones:
- strong shifts in the ground state emission from MQWs (Quantum Confined
Stark Effect);
- high sheet carrier densities (n_s~1-2 10^13 cm^-3) in AlGaN/GaN heterostructures,
without modulation doping;
- strong piezoelectric constants;
- apparent shift with the overlayer thickness of the measured valence
band offset by means of XPS.
The knowledge basis for the application of these heterostructures to
advanced optical and electronic devices requires an understanding of these
effects, which arise from the presence of strong polarization fields. The
origin of the polarization in nitride heterostrucures and several examples
of its manifestation, mainly based on the optical and electronic porperties
of AlGaN/GaN MBE heterostructures, will be discussed.
