IMPROVED UNIFORMITY OF CONTACT RESISTANCE IN GAAS-MESFET USING PD GE/TI/AU OHMIC CONTACTS/

Improved contact resistance uniformity, with a low resistance on high- low doped GaAs MESFET, was demonstrated using a Pd/Ge/Ti/Au ohmic cont act. 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 mo re 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 attrib uted to the uniform penetration of the ohmic junction into the buried high-doped channel layer by solid-state reactions, resulting in the im proved uniformity of device performance.