High doping effects on in-situ Ohmic contacts to n-InAs

We present the effect of active carrier concentration on the specific contact resistivity (ρ
_c
) of in-situ molybdenum (Mo) Ohmic contacts to n-type InAs. It is observed that, although the Fermi level pins in the conduction band for InAs, the contact resistivity decreases with the increase in InAs active carrier concentration. The lowest ρ
_c
obtained through transmission line model measurements was (0.6±0.4)×10
^-8
Ω-cm
²
for samples with 8.2×10
¹⁹
cm
^-3
active carrier concentration. The contacts were found to remain stable on annealing at 250°C for 1 hour.