Improved uniformity of contact resistance in GaAs MESFET using Pd/Ge/Ti/Au ohmic contacts

Abstract

Improved contact resistance uniformity, with a low resistance on high-low doped GaAs MESFET, was demonstrated using a Pd/Ge/Ti/Au ohmic contact. The lowest contact resistivity obtained was 2.8 x 10(-6) Ohm-cm(2). The average value and standard deviation (Delta Rc) of the contact resistance (Rc) were 0.73 and 0.07 Ohm-mm, respectively, which were more uniform than those for AuGe/Ni contacts with an average Rc of 0.77 Ohm-mm and Delta Rc of 0.16 Ohm-mm. The improved uniformity was attributed to the uniform penetration of the ohmic junction into the buried high-doped channel layer by solid-state reactions, resulting in the improved uniformity of device performance.