Heterointerface-engineered type Ⅱ SnO₂/boron-doped diamond heterojunction photodiodes with diverse diode characteristics and binary photoresponse

As an inevitable existence in semiconductor heterostructures, interfacial states have a non-negligible impact on the performance of heterojunction-based optoelectronic devices. Here, we develop high-performance photodiodes based on heterointerface-engineered type II SnO₂/boron-doped diamond (BDD) heterojunctions. We modulate the type of the interfacial states of SnO₂/BDD heterojunctions by changing the partial pressure of oxygen during the process of SnO₂ deposition by RF magnetron sputtering. As a result, backward rectifying, Zener, and forward rectifying diodes are obtained. The diversity of the diode characteristics is related to the carrier tunneling and avalanche multiplication effects. In addition, the I–V curve of the Zener diode has a negative differential resistance precursor under UV light irradiation. The photogenerated holes in the forward rectifier diode are easily trapped at the heterointerface during transmission. Zener and forward rectifier diodes can output positive and negative photocurrents (i.e., binary photoresponse) under on/off periodic light illumination owing to photovoltaic and pyro-phototronic effects. These results reveal the potential of SnO₂/BDD heterojunctions in the field of optical logic computing devices.