Effect of non-uniformly doped surface layer on the barrier height of a Schottky contact

The presence of a highly doped p-type surface layer at the interface of a metal n-type semiconductor Schottky contact increases the barrier height. An analysis of such an increase in barrier height is given for different impurity distributions in the surface layer. It has been shown that of the three distributions considered, namely exponential, Gaussian and erfc, the increase of barrier height (Δφ_B) is a maximum for the Gaussian and minimum for the exponential distribution. It is found that the increase of barrier height results in degradation of the diode ideality factor n, which can be minimised when Δφ_B is obtained by changing the doping concentration of the surface layer and keeping the thickness to a minimum.