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We report extremely low specific contact resistivity ͑ 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 4 OH, 14.8 normality͒, 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 c of ͑0.73± 0.44͒ ⍀ m 2-i.e., ͑7.3± 4.4͒ ϫ 10 −9 ⍀ cm 2-while TiW contacts exhibited c of ͑0.84± 0.48͒ ⍀ m 2. The TiW contacts are thermally stable, showing no observable degradation in resistivity after a 500°C annealing of 1 min duration.

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