High temperature stability of chromium boride ohmic contacts to p-type 6H-SiC |
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Authors: | T N Oder J R Williams M J Bozack V Iyer S E Mohney J Crofton |
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Affiliation: | (1) Department of Physics, Auburn University, 36849, AL;(2) Department of Materials Science and Engineering, The Pennsylvania State University, 16802 University Park, PA;(3) Department of Physics, Murray State University, 42071 Murray, KY |
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Abstract: | Ohmic contacts have been fabricated on p-type 6H-SiC using CrB2. Two hundred nanometer thick films were sputter-deposited on substrates of doping concentration 1.3×1019 cm−3 in a system with a base pressure of 3×10−7 Torr. Specific contact resistances were measured using the linear transmission line method, and the physical properties of
the contacts were examined using Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy, and transmission
electron microscopy. The as-deposited CrB2 contacts exhibited rectifying characteristics and contained oxygen as a major contaminant. Ohmic behavior with linear current-voltage
characteristics was observed following short anneals at 1100°C for 2 min at a pressure of 5×10−7 Torr. The oxygen in the CrB2 films was removed by the annealing process, and the lowest value of the specific contact resistance (rc) measured at room temperature was 8.2×10−5 Ω-cm2. Longer anneals at 1100°C for 3.5 h and 1200°C for 2 h reduced the room temperature values of r to 1.4×10−5 Ω-cm2. A thin reaction region has been identified at the CrB2/SiC interface; however, the interface remains essentially stable. Thermal stressing at 300°C in vacuum for over 2200 h produced
only a slight increase in the specific contact resistance. The low value of the specific contact resistance and the excellent
high temperature stability of the CrB2/SiC interface make this contact a candidate for high power/high temperature SiC device applications. |
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Keywords: | Chromium boride ohmic contact Rutherford backscattering spectrometry (RBS) specific contact resistance transmission electron microscopy (TEM) x-ray photoelectron spectroscopy (XPS) |
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