Charge-transport mechanisms in heterostructures based on TiO$_2$ : Cr$_2$O$_3$ thin films

$n$-TiO$_2$ : Cr$_2$O$_3$/$p$-Si anisotype heterostructures are fabricated by the deposition of a TiO$_2$ : Cr$_2$O$_3$ film by electron-beam evaporation onto a polished polycrystalline silicon substrate. Their electrical properties are studied and the dominant charge-transport mechanisms are determined: multistage tunneling-recombination mechanism involving surface states at the TiO$_2$ : Cr$_2$O$_3$/Si metallurgical interface under small forward biases and tunneling at biases exceeding 0.8 V. The reverse currents through the heterostructures under study are analyzed in terms of the single-stage tunneling mechanism of charge transport.