Ohmic contacts to n-type GaAs

We present a model of the metal–semiconductor junction, for heavily doped GaAs, so that tunneling dominates the current. It is assumed that the imaginary part of the wave vector in the semiconductor is given by the two-band model. Modifications in the barrier potential due to image charge, negative charge near the interface, and the degenerate doping of the semiconductor are included. The role of the L-point minimum in the GaAs in determining the position of the Fermi level in the semiconductor is included. The energy distribution of the conductance as a function of doping and barrier height is given. The contact resistance as a function of doping and barrier height is also presented. The results suggest that previous calculations are substantially in error due to the simple models that were used for the dependence of the imaginary part of the wave vector on energy.