Improved Al/Si ohmic contacts to p-type 4H-SiC

An AlSi-based ohmic contact with a new composition is reported in this paper, AlSi(2%)Ti(0.15%) contacts are formed by evaporation on p-type 4H-SiC: grown by liquid phase epitaxy (LPE) and annealed in the temperature range from 700 to 950 degreesC. The ohmic behaviour has been checked by I-V characteristics and the contact resistivity has been measured by the linear transmission-line-model (TLM) method. Thr dependence of the contact resistivity on the annealing conditions has been studied. An ohmic behaviour has been established at 700 degreesC while the lowest contact resistivity value of 9.6 x 10(-5) Omega cm(2) has been obtained after annealing at 950 degreesC. The thermal stability of both Al/Si/SiC and AlSiTi/SiC contacts at a temperature of 600 degreesC has been studied, It has been found that the AlSiTi/SiC contacts ale stable for 100 h at this ageing temperature while the Al/Si/SiC contacts deteriorate after 24 h. (C) 2001 Elsevier Science B.V. All rights reserved.