Correlation between morphological defects, electron beam-induced current imaging, and the electrical properties of 4H-SiC Schottky diodes
- Department of Electrical Engineering and Center for Solid State Electronics Research, Arizona State University, Tempe, Arizona 85287-5706 (United States)
Defects in SiC degrade the electrical properties and yield of devices made from this material. This article examines morphological defects in 4H-SiC and defects visible in electron beam-induced current (EBIC) images and their effects on the electrical characteristics of Schottky diodes. Optical Nomarski microscopy and atomic force microscopy were used to observe the morphological defects, which are classified into 26 types based on appearance alone. Forward and reverse current-voltage characteristics were used to extract barrier heights, ideality factors, and breakdown voltages. Barrier heights decrease about linearly with increasing ideality factor, which is explained by discrete patches of low barrier height within the main contact. Barrier height, ideality, and breakdown voltage all degrade with increasing device diameter, suggesting that discrete defects are responsible. Electroluminescence was observed under reverse bias from microplasmas associated with defects containing micropipes. EBIC measurements reveal several types of features corresponding to recombination centers. The density of dark spots observed by EBIC correlates strongly with ideality factor and barrier height. Most morphological defects do not affect the reverse characteristics when no micropipes are present, but lower the barrier height and worsen the ideality factor. However, certain multiple-tailed defects, irregularly shaped defects and triangular defects with 3C inclusions substantially degrade both breakdown voltage and barrier height, and account for most of the bad devices that do not contain micropipes. Micropipes in these wafers are also frequently found to be of Type II, which do not run parallel to the c axis.
- OSTI ID:
- 20664966
- Journal Information:
- Journal of Applied Physics, Vol. 97, Issue 1; Other Information: DOI: 10.1063/1.1829784; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ATOMIC FORCE MICROSCOPY
BREAKDOWN
CORRELATIONS
CURRENT DENSITY
ELECTRIC POTENTIAL
ELECTRICAL PROPERTIES
ELECTROLUMINESCENCE
ELECTRON BEAMS
EPITAXY
INCLUSIONS
LAYERS
LEAKAGE CURRENT
PLASMA
RECOMBINATION
SCANNING ELECTRON MICROSCOPY
SCHOTTKY BARRIER DIODES
SCREW DISLOCATIONS
SEMICONDUCTOR MATERIALS
SILICON CARBIDES
THIN FILMS