On the Determination of the Specific Contact Resistance of Alloyed Contacts to n-GaAs

Abstract

The popular distributed model for metal-semiconductor ohmic contacts is extended to take into account the nonplanar nature of alloyed contacts. AuGe/Ni ohmic contacts are fabricated on n-GaAs epitaxial layers (3×1018 cm-3, 160 nm) with an undoped cap layer of varied thickness. Thus the specific contact resistance and the so-called alloyed depth are determined from the measured contact resistances. Typical values are, respectively, 10-7 Ω·cm2 and 250 nm.