Theory of tunneling current in metal-semiconductor contacts with subsurface isotype δ-doping

The theory of tunneling current in metal-semiconductor contacts with subsurface isotype δ-doping is developed. Analytical expressions for current that take into account the decrease in the potential barrier height due to the image forces are obtained using the Murphy-Good approach. Characteristics of δ-doping that provide effective thermal field emission at the metal-semiconductor contact and a decrease in the effective barrier height from the original value to several kT are calculated. It is established that the main voltage dependence of the current in a contact with isotype δ-doping is exponential. It is shown that the nonideality factor can remain small (n≤1.07) for all values of the barrier height. A dramatic increase in n to the values n≥1.5 is typical of contacts with a partially depleted layer.