Extremely low resistance nonalloyed ohmic contacts on GaAs using InAs/InGaAs and InAs/GaAs strained-layer superlattices

Abstract

Employing a structure consisting of n+-InAs/InGaAs and InAs/GaAs strained-layer superlattices (SLS’s) grown by molecular beam epitaxy on GaAs films, nonalloyed contact resistances less than 8.5×10−8 Ω cm2 have been obtained. Self-consistent simulations show that these extremely small nonalloyed contact resistances are due to the suppression of the depletion depth in the GaAs channel and tunneling through the SLS layer. Similar structures on InGaAs channels have led to nonalloyed specific contact resistances of about 1.5×10−8 Ω cm2. These results represent the smallest figures reported for these important material systems.