Stable and reliable ohmic contact on p-type 4H-SiC up to 1500 h of aging at 600 °C

Abstract

The stability and reliability at high temperature of Ti3SiC2 based ohmic contacts on ptype 4H-SiC (0001) 4°-off substrates were studied. The contact was grown from Ti100-xAlx alloys annealed at high temperature (from 900°C to 1200°C). The Specific Contact Resistance (SCR) at room temperature and at high temperature (up to 600°C) was in the 10 -4 -10 -5 Ω.cm 2 range. A Schottky barrier height of 0.71 to 0.85 eV was calculated for the set of samples. After aging period at 600°C for 1500h, the SCR was very stable for Al contents x < 80 at%. This was correlated with chemical and physical stability of these contacts, where the residual stress located on 4H-SiC/Ti3SiC2 interface decreased after aging, for which the Ti3SiC2 phase was preserved. Whereas, in the case of x = 80 at%, the Ti3SiC2 phase disappeared and the contacts were not ohmic anymore after long time aging. The obtained results showed that Ti3SiC2/4H-SiC system is thermodynamically stable at high temperatures and can therefore be a good candidate, with high potential, for high power and high temperature electronic applications.