Formation of Effective CuI-GaN Heterojunction with Excellent Ultraviolet Photoresponsive Photovoltage

Here, the formation of an effective heterojunction with the p-type gamma-copper iodide (gamma-CuI) and n-type gallium nitride (GaN) with excellent photodiode characteristics is demonstrated. The gamma-CuI/GaN heterojunction shows good rectification characteristics up to applied bias voltage of +/- 20 V with low saturation current, thus confirming the suitability of the gamma-CuI film. The heterojunction diode and ultraviolet (UV) photoresponsive characteristics of the device are elucidated with temperature-dependent transport behavior analysis. With an increase in temperature, reverse saturation current is enhanced, whereas the diode ideality factor is reduced. The heterojunction device shows UV photoresponsive photovoltaic action with a prominent photovoltage of 0.93 V. The temperature-dependent photovoltaic action is also investigated in the temperature range of 298-373 K, where the open circuit voltage (V-oc) decreases with increase in temperature. The photovoltaic action is obtained at a temperature as high as 373 K, indicating that the gamma-CuI/GaN photoresponsive device is quite stable with excellent photovoltage. This study reveals that the effectiveness of gamma-CuI/GaN heterojunction and diode properties to fabricate a heterojunction photodiode with excellent photovoltage and photoresponsivity.