W/Pt/Ge/Pd contact optimization for the measurement of GaAs quantum structures

Abstract

The contribution deals with the optimization of Ge/Pd type ohmic contacts prepared with the help of laser annealing. The best results were obtained in the case of Pt/W/Ge/Pd/n/sup +/-GaAs and Pt/W/Pt/Ge/Pd/n/sup +/-GaAs contact structures (r/sub c//spl sim/4/spl times/10/sup -16/ /spl Omega/ cm/sup 2/). The optimal inert atmosphere for the laser annealing of these contacts is argon, the best metal for the overlayer of the contact is platinum. The quantum standard of resistance based on quantum Hall phenomena with the contact structure of W/Pt/Ge/Pd type is shown as an example. Good contact pads of the prepared sample have the resistance of about 500 /spl Omega/.