Interface characteristics of n-n and p-n Ge/SiC heterojunction diodes formed by molecular beam epitaxy deposition

Journal Article · Tue Jun 15 00:00:00 EDT 2010 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3449057· OSTI ID:21476334

Gammon, P M; Jennings, M R; Davis, M C; Roberts, G J; Covington, J A; Mawby, P A ^[1]; Perez-Tomas, A ^[2]; Shah, V A; Burrows, S E; Wilson, N R ^[3]; Boden, S A ^[4]

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1. School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom)
2. Centre Nacional de Microelectronica (IMB-CNM-CSIC), Campus UAB, 08193 Barcelona (Spain)
3. Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)
4. Engineering and Computer Science, University of Southampton, Highfield Campus, Southampton SO17 1BJ (United Kingdom)

In this article, we report on the physical and electrical nature of Ge/SiC heterojunction layers that have been formed by molecular beam epitaxy (MBE) deposition. Using x-ray diffraction, atomic force microscopy, and helium ion microscopy, we perform a thorough analysis of how MBE growth conditions affect the Ge layers. We observe the layers developing from independent islands at thicknesses of 100 nm to flat surfaces at 300 nm. The crystallinity and surface quality of the layer is shown to be affected by the deposition parameters and, using a high temperature deposition and a light dopant species, the layers produced have large polycrystals and hence a low resistance. The p-type and n-type layers, 300 nm thick are formed into Ge/SiC heterojunction mesa diodes and these are characterized electrically. The polycrystalline diodes display near ideal diode characteristics (n<1.05), low on resistance and good reverse characteristics. Current-voltage (I-V) measurements at varying temperature prove that all the layers have two-dimensional fluctuations in the Schottky barrier height (SBH) due to inhomogeneities at the heterojunction interface. Capacitance-voltage analysis and the SBH size extracted from I-V analysis suggest strongly that interface states are present at the surface causing Fermi-level pinning throughout the bands. A simple model is used to quantify the concentration of interface states at the surface.

• OSTI ID: 21476334
• Journal Information: Journal of Applied Physics, Vol. 107, Issue 12; Other Information: DOI: 10.1063/1.3449057; (c) 2010 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATOMIC FORCE MICROSCOPY
CRYSTAL GROWTH
DEPOSITION
ELECTRIC CONDUCTIVITY
FERMI LEVEL
FLUCTUATIONS
GERMANIUM
HELIUM IONS
HETEROJUNCTIONS
INTERFACES
LAYERS
MOLECULAR BEAM EPITAXY
P-N JUNCTIONS
POLYCRYSTALS
SEMICONDUCTOR MATERIALS
SILICON CARBIDES
SURFACES
X-RAY DIFFRACTION
CARBIDES
CARBON COMPOUNDS
CHARGED PARTICLES
COHERENT SCATTERING
CRYSTAL GROWTH METHODS
CRYSTALS
DIFFRACTION
ELECTRICAL PROPERTIES
ELEMENTS
ENERGY LEVELS
EPITAXY
IONS
MATERIALS
METALS
MICROSCOPY
PHYSICAL PROPERTIES
SCATTERING
SEMICONDUCTOR JUNCTIONS
SILICON COMPOUNDS
VARIATIONS