Low ohmic contacts to C-doped p-GaAs with Au/Zn/Au structure

The Au/Zn/Au metallisation scheme is investigated as a potential ohmic contact to C-doped p-type GaAs (4*10¹⁹ cm^-3, 1000 AA). Two alloying techniques, thermal and RTA, were investigated for different alloying times. The alloying times were optimised for the best contact resistance and a specific contact resistance of 3.6*10^-6 Omega cm², corresponding to a transfer resistance of 0.04 Omega mm, was achieved using RTA at 400 degrees C for 60 s. These contacts showed ohmic behaviour prior to any heat treatment.