High temperature ohmic contacts to 3C-SiC grown on Si substrates by chemical vapor deposition

Abstract

The properties of SiC have great potential for high temperature electronic device applications. For the realization of these devices the formation of stable (at elevated temperatures), low resistance ohmic contacts is required. For this purpose, multiple metallization schemes have been investigated on 3C-SiC grown on Si substrates by the chemical vapor deposition method. Both thick layers and thin multilayers of metals, deposited by electron beam evaporation, have been studied. Most of the metallizations exhibited ohmic behavior as-deposited even for relatively low doping levels due to the high concentration of defects in the SiC films. Annealing at temperatures up to 850 °C and ageing tests up to 550 °C were used to examine their thermal stability. The use of Al as contact overlayer instead of Au resulted in more stable contacts. The Cr/Ti/Pt/Mo/Al metal scheme produced the best results. On samples with doping (1–3) × 10 17 cm −3 an R c = 5.5 × 10 −6 Ω cm 2 was obtained while on samples with doping 3 × 10 18 cmu−3 an R c = 6 × 10 −7 Ωcm 2 before ageing and 7 × 10 −5 Ωcm 2 after 400 h at 550 °C was observed.