A reliable fabrication technique for very low resistance ohmic contacts to p-InGaAs using low energy Ar+ ion beam sputtering

A fabrication technique for non-alloyed Au/Pt/Ti ohmic contacts to p-InGaAs (N_A=1×10²⁰ cm^-3) is discussed. The semiconductor surface is cleaned by Ar⁺ ions immediately followed by the metal deposition by electron beam evaporation. The low energy (60 eV) Ar⁺ ion etching removes the residual oxide layer existent on the semiconductor surface. The contact is formed by rapid thermal processing (RTP) at 400±C. It is shown that extremely low specific contact resistances (r_c =6×10^-8 Ω-cm²) can be achieved, even for 2.5 μm contact widths, and that the contacts produced exhibit excellent homogeneity and improved uniformity over wet chemically pre-cleaned ones