As the reliability issues become more prevalent in the electronics industry, a properly engineered device must sustain its high performance characteristics not only under the ideal operating conditions but also under the hostile environments. Among many harsh environments that must be taken into considerations, the high temperature environment is the predominant concern for many industries, especially for automobile, aerospace, and military industry. In order for a device to properly operate and hold its original characteristics reliably at any elevated temperature for an extended period of time, one of the most critical requirements that must be met is the thermal stability of the ohmic contacts. This thesis presents the fabrication and characterization of the high temperature Ni/Al/Ti/Mo/Ge/In ohmic contacts to N-type GaAs. Important issues related to the ohmic contacts at an elevated temperature such as the specific contact resistance, spiking effect, and the surface passivation are examined. In order to provide a relativistic paint of view, the conventional non-high temperature Au/Ge/Ni/Ti ohmic contacts to N-type GaAs is also investigated and compared to the high temperature ohmic contacts. Finally, a brief invesxigation on the non-alloying Moms ohmic contacts is reported

Date of this Version

January 1993