Preparing Thermally Stable Ohmic Contacts for Gallium Arsenide Semi Conductor Devices
Original Publication Date: 1988-Jul-01
Included in the Prior Art Database: 2005-Feb-15
A technique is described whereby ohmic contacts are prepared so as to produce thermally-stable low-resistance contacts. Two preparation methods are described: Indium-Germanium coevaporation and implantation of Indium through the use of contact metals. Ohmic behavior in the contact material is believed to be due to a reduction of the barrier height, by ternary InGaAs phases, which exist at the metal/GaAs interfaces. Microstructure analysis and barrier height measurements indicate that this ternary phase layer is not continuous. This is because Indium will form islands when deposited onto the GaAs wafers at room temperature. Therefore, a significant reduction in the contact resistances of the contact metals can be expected by improving the uniformity of the ternary InGaAs layer thickness.