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

Abstract

Here, the formation of an effective heterojunction with the p‐type γ‐copper iodide (γ‐CuI) and n‐type gallium nitride (GaN) with excellent photodiode characteristics is demonstrated. The γ‐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 γ‐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 (Voc) decreases with increase in temperature. The photovoltaic action is obtained at a temperature as high as 373 K, indicating that the γ‐CuI/GaN photoresponsive device is quite stable with excellent photovoltage. This study reveals that the effectiveness of γ‐CuI/GaN heterojunction and diode properties to fabricate a heterojunction photodiode with excellent photovoltage and photoresponsivity.

Temperature-dependent device properties of γ-CuI and β-Ga2O3 heterojunctions

“…The bandgaps of the two materials as calculated from the absorption spectra were 3.02 and 4.6 eV for γ-CuI and β-Ga 2 O 3 , respectively. As discussed here, owing to the large differences in the electron affinity and work function, a significant built-in field ( Ga 2 O 3 − -CuI = V bi ) can be obtained at the interface of the γ-CuI/β-Ga 2 O 3 heterojunction [18,28]. Figure 2b shows a schematic diagram of the fabricated γ-CuI/β-Ga 2 O 3 vertical heterojunction device.…”

“…Thus, a suitable p-type wide-bandgap semiconductor as a counterpart for the n-type Ga 2 O 3 is significant for device fabrication [15,16]. γ-CuI with a bandgap of ~ 3.1 eV and p-type carrier mobility of ~ 40 cm 2 V −1 s −1 has been investigated for heterojunction devices with β-Ga 2 O 3 [17,18]. The lattice mismatch between the cubic phase γ-CuI (111) and β-Ga 2 O 3 along the c-axis is approximately 2%, indicating the possibility of fabricating a compatible heterostructure of γ-CuI (111) and β-Ga 2 O 3 for heterojunction device applications [19][20][21][22].…”

“…Previously, Ranade et al reported the integration of γ-CuI with gallium nitride (GaN), which is a III nitride widebandgap semiconductor, to form a p-n heterojunction with high-temperature stable photovoltaic action [18]. The successful fabrication of a γ-CuI/GaN heterojunction motivated us to explore the integration of p-type γ-CuI with β-Ga 2 O 3 .…”

Significant Enhancement in Optoelectronic Properties of γ-CuxAg1–xI Films Induced by Highly (111)-Preferred Orientation and Cu Content at Room Temperature

“…23 It is well established that AgI and CuI are both direct gap semiconductors. 24,25 Therefore, n = 1 was taken in Formula 1 in the case of Cu x Ag 1−x I. The band gaps were calculated from intercepts of the (αhν) 2 − hν curve, which are displayed in Figure 4b.…”

“…“ n ” is defined by the indirect ( n = 4) of direct ( n = 1) band gap type of the semiconductors . It is well established that AgI and CuI are both direct gap semiconductors. , …”