On the determination of the specific contact resistance of alloyed contacts to n-GaAs

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 (3×10 18 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·cm 2 and 250 nm.