Schottky Barrier Diode Characteristics of Graphene-GaN Heterojunction with Hexagonal Boron Nitride Interfacial Layer

Metal-insulator-semiconductor (MIS) based Schottky barrier diode (SBD) has significant importance for optoelectronics and other device applications. Here, we demonstrate the fabrication of a highly rectifying Schottky barrier diode (SBD) using a thin hexagonal boron nitride (hBN) interfacial layer in graphene and n-type gallium nitride (n-GaN) heterojunction. Significant reduction of reverse saturation current is obtained with the introduction of hBN layer in graphene/n-GaN interface. The MIS based SBD shows excellent ultraviolet (UV) photoresponsivity with a light/dark ratio of approximate to 10(5) at a low reverse bias voltage (-1.5V). Temperature dependent current density-voltage (J-V) characteristics of the graphene/hBN/n-GaN heterojunction is investigated to elucidate the current transport behavior. The Schottky barrier height increased with increase in temperature from 0.77 to 0.98eV in the temperature range of 298-373K, respectively. The series resistance (R-S) is also found to be temperature dependent, where R-S decreased with increase in temperature. The understanding of graphene/hBN/n-GaN heterojunction device characteristics can be significant for photodiode and switching device applications.