Titanium Tungsten (TiW) for Ohmic contacts to n-and p-type 4H-SiC

Abstract

ABSTRACTIn the present work, we investigated sputtered titanium tungsten (TiW) contacts for Ohmic contacts to both n- and p-type 4H-SiC with long-term stability under high temperature (500°C).. Epitaxial layers with a doping concentration of 1.3×1019 and 6×1018 cm−3 were used. After high temperature annealing (>950°C) sputtered TiW contacts showed Ohmic behavior with good uniform distribution of the specific contact resistance. We obtained an average specific contact resistance (pc) of 4×10−5 Ωcm2 and 1.2 ∼ 1.7×10−4 Ωcm2 for p- and n-type, respectively from linear TLM measurement. We also found some variation of the specific contact resistance and the sheet resistance from our TLM measurement for p-type contacts. We will discuss this behavior with the measurement of SIMS. Long-term stability with a top-cap layer is also discussed