P-type ohmic contacts to AlGaAs/GaAs heterostructures

Abstract

Ohmic contacts to p-AlGaAs/GaAs heterostructures have larger resistivities compared to n-type structures because holes are heavier than electrons and the heterointerface barrier for high mobility structures is thicker. This work shows that diffusion of Zn during an alloy process of a Au/Zn/Au metallization establishes high acceptor concentrations throughout the heterostructure resulting in a thin metal-semiconductor barrier and probably a degradation of the heterointerface barrier by disordering, while the heterostructure outside the contact region remains unchanged. Contact resistivities down to 3.5ωmm at 25K could thus be achieved.