Published online by Cambridge University Press: 25 February 2011
Electrical, structural and diffusion characteristics of a solid phase reacted ohmic contact to n-GaAs are studied. Attempts were made to form a low band gap interfacial phase of InGaAs to reduce the barrier height at the conductor/semiconductor junction and thus yielding a low resistance, high reliablity contacts. The understanding of the interface is important from the point of view of device performance as well as device reliability. The contacts were fabricated by co-sputtering W, In and Te targets on n-GaAs with subsequent annealing. The as-deposited rectifying contacts became ohmic when annealed to 500°C, and showed a specific contact resistance of ∽5×10-6 ohm cm2. The Auger and Rutherford back scattering analysis of the interface revealed an InGaAs phase formation prior to the onset of ohmic conduction. The contacts were stable up to 500°C and the surface morphology was superior to presently used AuNiGe contacts. The contact pads were patterned by dry plasma etching without adversely affecting the GaAs substrate.