Contacts on GalnAs

The specific contact resistance ρcof Ni/Au-Ge/Ni and Ni/Au-Sn/Ni layers on n-GaInAs and Ni/Au-Mg/Ni and Ni/Au-Zu/Ni on p-GaInAs are measured for different alloying temperatures and times using an extended transmission line model. Specific contact resistances of 4.10^-8Ω cm²for Ni/Au-Sn/Ni on n-GaInAs (n = 10¹⁸cm^-3) and 2.10^-5Ω. cm²for Ni/Au-Zn/Ni on p-GaInAs (p = 10¹⁸cm^-3) are obtained. After deposition at room temperature, the barrier height of the metal-n-GaInAs system was determined to be 0.16 eV, decreasing below 20 meV after heat treatment. Interdiffusion of metal and semiconductor was investigated by SIMS/Auger measurements. At alloying temperature of 300°C the contacts show fast diffusion of Au relative to the dopants, effecting an increase of the specific contact resistance.