The formation and thermal stability of multilayer ohmic contacts to n-GaAswith TiBx and Mo diffusion barriers

Thermal degradation of Au/Mo/TiBx/AuGe multilayer ohmic contacts with Mo an d TiBx diffusion barriers was studied. The contacts were employed in Gunn-e ffect diodes. Depth profiling of the components in the contacts was perform ed using Auger electron spectroscopy. The microrelief of the metal/semicond uctor interface and contact surface morphology were examined with atomic fo rce microscopy and scanning electron microscopy, respectively. The measurem ents were taken before and after argon annealing at T = 400, 600, or 800 de greesC for 60 s. The resistance of the Gunn diode mesa was also measured. A nnealing at 400 degreesC is shown not to affect the sandwich structure of t he contacts. Annealing at 600 degreesC causes structure rearrangement in th e layers up to cracking. It is found that the thermal threshold of degradat ion of the Au/Mo/TiBx /AuGe/GaAs structure depends on the resistance of the TiBx layer to thermal effects. Reasons for the degradation of Mo and TiBx antidiffusion properties are discussed. (C) 2000 MAIK "Nauka / Interperiodi ca".