Improvement of Ohmic contacts to In0.65Ga0.35Sb using Mo refractory metal and surface preparation for 6.3 Å heterojunction bipolar transistors

This article describes a comparative study of Ti/Au, Ti/Pd/Au, Ti/Pt/Au, Mo/Au, Mo/Pt/Au, and Pd/Mo/Pt/Au Ohmic contacts to both n- and p-In0.65Ga0.35Sb. For In0.65Ga0.35Sb:Te doped to 2×1018 cm-3, specific contact resistivities ρc below 2×10-6 Ω cm2 were demonstrated. Lower ρc in the 10-7 Ω cm2 range were also achieved for In0.65Ga0.35Sb:C doped to 4.5×1019 cm-3. The influence of surface preparation has been investigated on unannealed Mo/Pt/Au contacts and further improvements of the specific contact resistivities to as low as (8.7±0.7)×10-7 and (2.9±1.7)×10-8 Ω cm2 have been achieved for n- and p-InGaSb, respectively.