Metal–Semiconductor–Metal ε-Ga₂O₃ Solar-Blind Photodetectors with a Record-High Responsivity Rejection Ratio and Their Gain Mechanism

Abstract

In recent years, Ga2O3 solar-blind photodetectors (SBPDs) have received great attention for their potential applications in solar-blind imaging, deep space exploration, confidential space communication, etc. In this work, we demonstrated an ultra-high-performance ε-Ga2O3 metal–semiconductor–metal (MSM) SBPD. The fabricated photodetectors exhibited a record-high responsivity and fast decay time of 230 A/W and 24 ms, respectively, compared with MSM-structured Ga2O3 photodetectors reported to date. Additionally, the ε-Ga2O3 MSM SBPD presents an ultrahigh detectivity of 1.2 × 1015 Jones with a low dark current of 23.5 pA under an operation voltage of 6 V, suggesting its strong capability of detecting an ultraweak signal. The high sensitivity and wavelength selectivity of the photodetector were further confirmed by the record-high responsivity rejection ratio (R 250 nm/R 400 nm) of 1.2 × 105. From the temperature-dependent electrical characteristics in the dark, the thermionic field emission and Poole–Frenkel emission were found to be responsible for the current transport in the low and high electric field regimes, respectively. In addition, the gain mechanism was revealed by the Schottky barrier lowering effect due to the defect states at the interface of the metal contact and Ga2O3 or in the bulk of Ga2O3 based on current transport mechanism and density functional theory calculations. These results facilitate a better understanding of ε-Ga2O3 photoelectronic devices and provide possible guidance for promoting their performance in future solar-blind detection applications.

A Self‐Powered Ultraviolet Photodetector with Ultrahigh Photoresponsivity (208 mA W−1) based on SnO2 Nanostructures/Si Heterojunctions

“…PD-SL-NSs possesses a superior specific detectivity of 1.58 Â 10 13 Jones and a higher LDR of 51 dB, indicating that PD-SL-NSs has the strong ability to acquire high signal to noise ratio. [19] Meanwhile, as for self-powered mode, i.e., under zero bias, it exhibits a relatively high detectivity of 1.17 Â 10 12 Jones and a higher LDR of 46 dB. Table 1 compares the performance parameters of the photodetectors.…”

Avalanche Effect and High External Quantum Efficiency in MgZnO/Au/ZnO Sandwich Structure Photodetector

“…Therefore, this strongly illustrates that defects or interface states within the film and the M-S barrier play a crucial role in determining the current transport mechanism. [25][26][27][28] Current and voltage show strong dependence on the further increase in the voltage (>65 V). It shows that a new gain mechanism has played a role under high bias.…”

“…Therefore, this strongly illustrates that defects or interface states within the film and the M–S barrier play a crucial role in determining the current transport mechanism. [ 25–28 ]…”

Status and Outlook of Metal–Inorganic Semiconductor–Metal Photodetectors

“…found that using ε‐Ga 2 O 3 , the gain of MSM‐PDs could reach 1150; meanwhile, the response speed was not too slow (24 ms). [ 136 ]…”