A broadband self-powered UV photodetector of a β-Ga₂O₃/γ-CuI p-n junction

Abstract

The symmetric Ti/Au bi-layer point electrodes have been successfully patterned on the β-Ga2O3 films which are prepared by metal–organic chemical vapor deposition (MOCVD) and the γ-CuI films which are prepared by spin-coating. The fabricated heterojunction has a large open circuit voltage (V oc) of 0.69 V, desired for achieving self-powered operation of a photodetector. Irradiated by 254-nm ultraviolet (UV) light, when the bias voltage is –5 V, the dark current (I dark) of the device is 0.47 pA, the photocurrent (I photo) is –50.93 nA, and the photo-to-dark current ratio (I photo/I dark) reaches about 1.08 × 105. The device has a stable and fast response speed in different wavelengths, the rise time (τ r) and decay time (τ d) are 0.762 s and 1.741 s under 254-nm UV light illumination, respectively. While the τ r and τ d are 10.709 s and 7.241 s under 365-nm UV light illumination, respectively. The time-dependent (I–t) response (photocurrent in the order of 10−10 A) can be clearly distinguished at a small light intensity of 1 μW⋅cm−2. The internal physical mechanism affecting the device performances is discussed by the band diagram and charge carrier transfer theory.

A self-powered ultraviolet photodetector based on a Ga2O3/Bi2WO6 heterojunction with low noise and stable photoresponse

“…Many materials have been reported to form heterojunctions with Ga 2 O 3 , such as graphene, Ti 3 C 2 , BiFeO 3 , CsCu 2 I 3 , PEDOT:PSS, WO 3 , CuI, and ZnO. [15][16][17][18][19][20][21][22][23] Li's research confirmed that a heterostructure PD possesses a certain improvement in light response compared with a single-material PD. [24] The rise and decay times of Ga 2 O 3 /CuSCN heterojunction photodetectors are 0.19 s and 0.16 s, faster than those of independent CuSCN and Ga 2 O 3 devices, indicating that the constructed n-Ga 2 O 3 /p-CuSCN heterojunction can effectively improve the photoresponse speed.…”

Ultrasensitive Dual-Junction-Coupled n-ZnO/n-Ga2O3/p-GaN-Based Self-Driven Broad-Band Ultraviolet Photodetector

“…For example, Tang et al studied p-NiO/n-Ga 2 O 3 photodetectors; under zero bias, the device responsivity was 57 μA/W, and its detectivity was 5 × 10 9 Jones . Based on the Schottky, heterojunction, or p–n junction designs, photodetectors can use the associated built-in electric field to separate and transport photogenerated carriers, which possess obvious advantages of no need of external driving electric source, fast response, and easy integration. − …”

Transparent p-type CuI film based self-powered ultraviolet photodetectors with ultrahigh speed, responsivity and detectivity

“…8–11 Yet, CuI is far from being fully exploited as a transparent p-type semiconductor and further study is still required toward improved properties and possible applications. So far, CuI has been reported to be integrated with ZnO, 12–16 Ga 2 O 3 , 17,18 TiO 2 , 19,20 IGZO, 21 n type Si (n-Si), 22 etc. to construct CuI-based ultraviolet (UV) photodetectors.…”