Pt/Ti/p-In sub (0.53) Ga sub (0.47) As Low Resistance Nonalloyed Ohmic Contact Formed by Rapid Thermal Processing.
01 January 1989
Low resistance nonalloyed Ohmic contacts of E-gun evaporated Pt/Ti to 1.5.10 sup (19) cm sup (-3) Zn doped In sub (0.53) Ga sub (0.47) As have been formed by Rapid Thermal Processing. These contacts were ohmic already as-deposited with a specific contact resistance value of 3.0.10 sup (-4) OMEGAcm sup 2. Increasing the heating temperature led to decrease of the specific contact resistance to an extremely low value of 3. 4.10 sup (-8) OMEGAcm sup 2 as a result of Rapid Thermal Processing at 450C for 30 sec. This treatment caused very limited interfacial reaction between the Ti and the InGaAs and resulted in the formation of a Ti ad As binary reacted layer (about 10 nm thick) adjacent to the substrate as well as a reaction between the In and As (about 10 nm thick) above it. Heating at temperatures higher than 500C resulted in an extensive interaction and degradation of the contact. Heating at 450C for 30 sec caused tensile stress of 5.6.10 sup 9 dyne cm sup (-2) at the Ti/Pt bilayer, but the metal adhesion remained strong.