Isotopic Homojunction Band Engineering from Diamond
H. Watanabe,*
C. E. Nebel,
S. Shikata
Confinement of charge carriers in semiconductors by quantum
wells is usually accomplished with layers that vary in elemental
composition, such as aluminum gallium arsenide and gallium arsenide.
We fabricated diamond superlattices by creating multilayer structures
of isotopically pure carbon isotopes carbon-12 (
12C) and carbon-13
(
13C), which confine electrons by a difference in band-gap energy
of 17 millielectron volts. Cathodoluminescence experiments performed
at 80 kelvin showed that excitonic recombination in the higher-energy
band of
13C vanishes in favor of increased recombination in
the lower-energy
12C material. Carrier confinement was achieved
in diamond superlattices made up of both thinner (30 nanometers)
and thicker (up to 350 nanometers) layers.
Present address: Fraunhofer Institut für Angewandte Festkörperphysik, Tullastrasse 72, 79108 Freiburg, Germany.
* To whom correspondence should be addressed. E-mail: hideyuki-watanabe{at}aist.go.jp
