High temperature and high power stability investigation of Al-based ohmic contacts to p-type 4H-SiC

Three types of low resistivity Al-based ohmic contacts to p-type 4H-SiC, Au/Al/Si, Au/AlSiTi and Au/Ti/Al have been studied. Reproducible contact resistivity of 8.30/spl times/10/sup -5/ /spl Omega/cm/sup 2/, 6.42/spl times/10/sup -5/ /spl Omega/cm/sup 2/ and 1.42/spl times/10/sup -5/ /spl Omega/cm/sup 2/ has been obtained for Al/Si, AlSiTi and Al/Ti contacts, respectively. The investigation of the thermal properties of Al-based contacts shows that addition of Ti to the contact composition improves its stability at ageing temperatures as high as 700/spl deg/C, at operating temperatures up to 450/spl deg/C and current densities of 10/sup 3/ A/cm/sup 2/. XPS analysis of as-deposited and annealed contacts has been performed to explain the observed thermal properties.