Low-resistive metal/n⁺-InAsSb/n-GaSb contacts

We present low-resistive electrical contacts to n-type GaSb with Te doping of 5 × 10¹⁷ cm^-3 using a Ti/Pt/Au (1/35/275 nm) metalization sequence and an intermediate InAsSb contact layer with n-doping of 1 × 10²⁰ cm^-3 (also Te). The high doping level is achieved during growth, so in-diffusion of dopants is not required. To reduce the impact of the native oxide layer we remove it in a sputter-etching process using Ar ions and afterwards deposit the metalization in the same chamber. No annealing is necessary to achieve ohmic IV-characteristics with a resistivity as low as 5.1 × 10^-6 Ω cm². It improves to 3. 3 × 10^-6 Ω cm² after annealing at 350 °C for 90 s. The resistivity slightly increases for deeper etching of the native oxide, which is probably due to surface damage induced during the sputter-etching process.