The features of contact resistivity behavior at helium temperatures for   InP- and GaAs-based ohmic contacts
  Contact resistivity rc of InP and GaAs based ohmic contacts was measured in the 4.2/300 K temperature range. Nonmonotonic dependences rc(T), with a minimum at temperature 50 K (150 K) for InP (GaAs) based contacts were obtained. The results can be explained within the framework of the mechanism of current flow through metal shunts (associated with dislocations) penetrating into the semiconductor bulk, with allowance being made for electron freeze-out at helium temperatures. Contact ohmicity in the 4.2/30K temperature range is due to accumulation band bending near shunt ends at the metal/semiconductor interface. 
A.V. Sachenko, A.E. Belyaev, N.S. Boltovets, S.A. Vitusevich, R.V.   Konakova, S.V. Novitskii, V.N. Sheremet
cond-mat.mtrl-sci