Ultra‐High Performance Amorphous Ga₂O₃ Photodetector Arrays for Solar‐Blind Imaging

Abstract

The growing demand for scalable solar-blind image sensors with remarkable photosensitive properties has stimulated the research on more advanced solar-blind photodetector (SBPD) arrays. In this work, the authors demonstrate ultrahigh-performance metal-semiconductor-metal (MSM) SBPDs based on amorphous (a-) Ga 2 O 3 via a post-annealing process. The post-annealed MSM a-Ga 2 O 3 SBPDs exhibit superhigh sensitivity of 733 A/W and high response speed of 18 ms, giving a high gain-bandwidth product over 10 4 at 5 V. The SBPDs also show ultrahigh photo-to-dark current ratio of 3.9 × 10 7 . Additionally, the PDs demonstrate super-high specific detectivity of 3.9 × 10 16 Jones owing to the extremely low noise down to 3.5 fW Hz −1/2 , suggesting high signal-to-noise ratio. Underlying mechanism for such superior photoelectric properties is revealed by Kelvin probe force microscopy and first principles calculation. Furthermore, for the first time, a large-scale, high-uniformity 32 × 32 image sensor array based on the post-annealed a-Ga 2 O 3 SBPDs is fabricated. Clear image of target object with high contrast can be obtained thanks to the high sensitivity and uniformity of the array. These results demonstrate the feasibility and practicality of the Ga 2 O 3 PDs for applications in solar-blind imaging, environmental monitoring, artificial intelligence and machine vision.

Ultra‐Sensitive β‐Ga2O3 Solar‐Blind Photodetector with High‐Density Al@Al2O3 Core−Shell Nanoplasmonic Array

“…[23,47,48] Figure 3a,b exhibit the schematic diagram and SEM images (Figure S5, Supporting Information, for more scales/locations) of the β-Ga 2 O 3 MSM PD with an Al nanostructure array, whose ultrahigh density as well as homogeneous dispersion in the active area is clearly demonstrated in the latter, showing great potential to construct a PD array in future. [49] As shown in Figure 3c, the Ti/Al stack electrodes present a back-to-back Schottky contact, [50] contributing to the low dark currents (I dark 's) in all samples. As well known, it is difficult to achieve the ohmic contact on the UWBG semiconductor β-Ga 2 O 3 without some special treatments/preconditions (often simultaneously required), including heavy doping, impurity activation, surface etching modification, and contact annealing.…”

High-Performance Solar-Blind UV Phototransistors Based on ZnO/Ga2O3 Heterojunction Channels

“…Solar-blind ultraviolet (UV, 200–280 nm, a black background on the earth) photodetectors (PDs) have attracted much attention for many applications such as satellite communications, fire alarms, and environmental monitoring. − Generally, wide band gap semiconductors are preferred to solar-blind UV PDs because they have a high UV/visible rejection ratio that makes them unnecessary to filter out the light with longer wavelengths. Among the wide band gap semiconductors, Ga 2 O 3 is considered an ideal candidate for solar-blind PD applications for its wider band gap (good solar-blind/near ultraviolet rejection ratio) and higher responsivity. − Over the past decade, a number of research efforts have been conducted on Ga 2 O 3 PDs with various Ga 2 O 3 growth approaches including metal–organic chemical vapor deposition (MOCVD), molecular-beam epitaxy (MBE), etc. − However, most of them are based on single-crystal β-Ga 2 O 3 that requires strictly controlled fabrication processes. − In contrast, amorphous (or nanocrystalline) Ga 2 O 3 thin films are more attractive due to the advantages of low cost, easy fabrication, low-temperature process, and tunable band gaps. , …”

“…19−25 In contrast, amorphous (or nanocrystalline) Ga 2 O 3 thin films are more attractive due to the advantages of low cost, easy fabrication, low-temperature process, and tunable band gaps. 26,27 There are mainly two kinds of UV PDs based on Ga 2 O 3 : photoconductor and photovoltaic. 13 The photoconductor PD is simple, but the photocurrent of PDs is limited by the mobility of the semiconductors.…”

Pressure‐Tuning Photothermal Synergy to Optimize the Photoelectronic Properties in Amorphous Halide Perovskite Cs3Bi2I9

“…[34][35][36] The thermoelectric applications require excellent electrical conductivity, which is a considerable challenge in amorphous materials, [32] and generally, the wide bandgap results in photoelectric applications mainly being limited to the solar-blind region. [37,38] Fortunately, this can be addressed in amorphous perovskites owing to the bandgap reduction and metallization occurring in the pressurization process. [22,29] As a critical photoresponse mechanism, the photothermoelectric effect combines photothermal conversion processes and the thermoelectric effect and can achieve a broadband photoresponse with a self-powered operation capability under zero external bias.…”