Low resistance, nonalloyed Ohmic contacts to InGaAs

摘要

We report extremely low specific contact resistivity (ρ_C) nonalloyed Ohmic contacts to n-type In_(0.53)Ga_(0.47)As, lattice matched to InP. Contacts were formed by oxidizing the semiconductor surface through exposure to ultraviolet-generated ozone, subsequently immersing the wafer in ammonium hydroxide (NH_4OH, 14.8 normality), and finally depositing either Ti/Pd/Au contact metal by electron-beam evaporation or TiW contact metal by vacuum sputtering. Ti/Pd/Au contacts exhibited ρ_c of (0.73±0.44) Ω μm~2—i.e., (7.3±4.4) × 10~(-9) Ω cm~2—while TiW contacts exhibited p_c of (0.84±0.48) Ω μm~2. The TiW contacts are thermally stable, showing no observable degradation in resistivity after a 500 ℃ annealing of 1 min duration.