Features of Ohmic Contact with an Ion-Induced p-GaAs Nanolayer

The properties of a metal contact with a p-GaAs layer ~8 nm thick induced by low-energy Ar+ ions on an n-GaAs wafer as a result of the conduction type conversion have been studied. The metal was deposited according to the standard technology on the surface of the semiconductor p-GaAs with a natural oxide layer partially restored when the sample was transferred to a deposition setup. To prevent metallization of the nanolayer the contact was not annealed. Therefore, a Schottky barrier emerged at the interface and a residual oxide layer retained. However, current–voltage characteristics showed that the formed contact is predominantly ohmic. It has been found that a high concentration of ion-induced defects radically reduces the width of the Schottky barrier and ensures the tunneling of holes and electrons of the semiconductor valence band through the barrier in the forward and reverse directions, respectively. It has been shown that ion bombardment of the p-GaAs semiconductor surface makes it possible to obtain an ohmic contact with any metal without annealing. It is concluded that the ion-stimulated modification of the semiconductor and the exclusion of annealing make it possible to obtain a tunnel ohmic contact with an extremely thin p-GaAs nanolayer coated with the residual layer of natural oxide.