Low resistance ohmic contacts on nitrogen ion bombarded InP

Nonalloyed Ti/Pt/Au contacts deposited in situ onto nitrogen ion bombarded n-type InP show contact resistivities as low as 3.4×10−6 Ω cm2. Acceleration voltages of 100–300 V and exposure times of 3–11 min were used to remove InP native oxide and produce a shallow (≤300 Å) disordered donor layer on which ohmic contacts were deposited. Electron diffraction patterns matching those of polycrystalline InN were identified in this degenerately doped surface layer, which was further characterized by secondary ion mass spectrometry and ion channeling. Similar layers produced by Ar ion bombardment under the same conditions showed much higher contact resistivities (∼10−4 Ω cm2), indicating that the InN formation is beneficial for contact properties.