Free carrier accumulation at cubic AlGaN/GaN heterojunctions
- Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States)
- Department of Physics, Universitaet Paderborn, D-33098 Paderborn (Germany)
Cubic Al{sub 0.3}Ga{sub 0.7}N/GaN heterostructures were grown by plasma-assisted molecular beam epitaxy on 3C-SiC (001) substrates. A profile of the electrostatic potential across the cubic-AlGaN/GaN heterojunction was obtained using electron holography in the transmission electron microscope. The experimental potential profile indicates that the unintentionally doped layers show n-type behavior and accumulation of free electrons at the interface with a density of 5.1 x 10{sup 11}/cm{sup 2}, about one order of magnitude less than in wurtzite AlGaN/GaN junctions. A combination of electron holography and cathodoluminescence measurements yields a conduction-to-valence band offset ratio of 5:1 for the cubic AlGaN/GaN interface, which also promotes the electron accumulation. Band diagram simulations show that the donor states in the AlGaN layer provide the positive charges that to a great extent balance the two-dimensional electron gas.
- OSTI ID:
- 22025502
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 14 Vol. 100; ISSN APPLAB; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM COMPOUNDS
CATHODOLUMINESCENCE
CUBIC LATTICES
DOPED MATERIALS
ELECTRON DENSITY
ELECTRONIC STRUCTURE
GALLIUM NITRIDES
HETEROJUNCTIONS
HOLOGRAPHY
INTERFACES
LAYERS
MOLECULAR BEAM EPITAXY
PLASMA
SEMICONDUCTOR MATERIALS
SILICON CARBIDES
SUBSTRATES
TRANSMISSION ELECTRON MICROSCOPY
TWO-DIMENSIONAL CALCULATIONS
VALENCE