Highly Stable W/p-ln sub (0.53) GaAs sub (0.47) Ohmic Contacts for Self-Aligned Buried Heterostructure Laser Fabrication.

Tungsten contacts to Zn doped In sub (0.53) Ga sub (0.47) As have been formed by rapid thermal processing. Contacts to layers with Zn doping concentration of 5 x 10 sup (18) cm sup (-13) were rectifying as sputter deposited as well as after heat treatments at temperatures lower than 450C. Higher processing temperatures caused a linear decrease of the contact resistivity values from 0.6 as deposited to 0.15omega mm after heating at 550C. Rapid thermal processing at these higher temperatures stimulated the Schottky to ohmic contact conversion with minimum contact resistance value of 8.5 x 10 sup (-5) OMEGA cm sup 2 and sheet resistance value of 150 OMEGA/square as a result of heating at 600C for 30 sec. By increasing the p-InGaAs doping level to 1 x 10 sup (19) cm sup (-3) the specific resistance of this contact was dropped to the minimum of 7.5 x 10 sup (-6) OMEGA cm sup 2 as a result of heating at 500C for 30 sec.