Fig1.
$I$--$V$ characteristics of the Ti (50 nm)/Al/Au contact before and after annealing at 1050 ℃.
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| Citation: |
Chao Han, Yuming Zhang, Qingwen Song, Xiaoyan Tang, Hui Guo, Yimen Zhang, Fei Yang, Yingxi Niu. Interface annealing characterization of Ti/Al/Au ohmic contacts to p-type 4H-SiC[J]. Journal of Semiconductors, 2015, 36(12): 123006. doi: 10.1088/1674-4926/36/12/123006
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C Han, Y M Zhang, Q W Song, X Y Tang, H Guo, Y M Zhang, F Yang, Y X Niu. Interface annealing characterization of Ti/Al/Au ohmic contacts to p-type 4H-SiC[J]. J. Semicond., 2015, 36(12): 123006. doi: 10.1088/1674-4926/36/12/123006.
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Interface annealing characterization of Ti/Al/Au ohmic contacts to p-type 4H-SiC
DOI: 10.1088/1674-4926/36/12/123006
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Abstract
Ti/Al/Au ohmic contacts to p-type 4H-SiC in terms of a different annealing time and Ti composition are reported. At 1050℃, proper increase in annealing time plays a critical role in the Schottky to ohmic contact conversion. With the optimized annealing time, the contact with a high Ti content yields a lower specific contact resistivity(ρc) of 6.4×10-5 Ω·cm2 compared with the low-Ti contact. The annealed surface morphology and phase resultants were examined by scanning electron microscopy(SEM) and X-ray diffraction(XRD), respectively. For the better ohmic contact, element distribution and chemical states were qualitatively identified by X-ray photoelectron spectroscopy(XPS) depth analysis. In particular, the presence of C and a Si-related phase was discussed and associated with the change in the surface status of the as-grown epilayer of 4H-SiC during annealing. The results reveal that the out-diffused C and Si atoms, with an approximate atomic ratio of 1:1 in the contact layer, can combine to form an amorphous Si-C state. The polycrystalline graphite instead of an unreacted C cluster in the whole alloyed structure and an extra nanosize graphite flake on the outermost surface of the annealed contact were confirmed by Raman spectroscopy. -
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