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

Abstract

β‐Ga2O3 solar‐blind photodetectors (PDs) are attracting great attention for broad applications. However, their detection sensitivities are still lower than expected after tremendous efforts. The phenomenon of localized surface plasmon resonance (LSPR) offers another approach beyond conventional techniques to engineer the photodetection performance, but extending the plasmonic properties into the deep‐ultraviolet region faces severe challenges, among which strictly controlling the nanostructures structural properties is extremely prominent besides material selection. Herein, well‐defined Al@Al2O3 core−shell nanostructure arrays are fabricated with sub‐50 nm feature sizes, narrow dimension distributions, periodic graphene‐like patterns, and extremely high densities (up to 152.7 counts µm−2). The decorated β‐Ga2O3 PDs exhibit significantly enhanced sensitivities without response spectra broadening. Particularly, the sample with a 42‐nm nanostructure array possesses an ultrahigh specific detectivity (4.22 × 1015 Jones), being one of the top among film‐type gallium oxide PDs, and an excellent responsivity of 216.0 A W−1 peaked at 235 nm. Moreover, the passivation effect of self‐terminating native oxide shell is confirmed. The finite‐difference time‐domain simulations based on isolated, dimer, and arrayed models not only demonstrate the presence of LSPR, but also reveal the critical contribution of nanostructure density. The findings provide an alternative platform to break the bottleneck and develop ultra‐sensitive, truly solar‐blind PDs for advanced optoelectronic systems.

Promoting 2D Material Photodetectors by Optical Antennas beyond Noble Metals

“…For example, by modifying a well-defined Al@Al 2 O 3 core-shell nanostructure array, Qian et al demonstrated an improvement in the responsivity of the 𝛽-Ga 2 O 3 photodetector by more than four times. [134] Therefore, by reasonably matching and coupling these non-precious metal optical antennas with 2DLMs, the photosensitivity of 2DLM photodetectors can theoretically be significantly improved.…”

Plasmon-induced hot carrier dynamics and utilization

“…Qian et al. combined Al/Al2normalO3 core–shell nanostructure arrays with β-Ga2O3 solar-blind photodetectors by the nanosphere lithography, which exhibits a sharp plasmon resonance peak at 235 nm belonging to the solar-blind UV region (200–280 nm) that hardly reaches the surface of the Earth [357] . An excellent responsivity (216 A/W) and ultrahigh specific detectivity (4.22×1015 Jones) are achieved.…”

Regulation of oxygen vacancies in nitrogen-doped Ga2O3 films for high-performance MSM solar-blind UV photodetectors

“…Solar-blind photodetectors have attracted widespread attention due to their extensive applications such as optical communication, heavy weapon monitoring, missile tracking, ozone hole monitoring, imaging technology and explosion and flame detection. [1][2][3][4] Wide band gap semiconductors are deemed as promising materials for manufacturing SBPDs. Among them, Ga 2 O 3 with an ultra-wide bandgap of 4.4-5.3 eV corresponding to the solar-blind spectrum region between 238 and 280 nm is a natural material used for solar-blind ultraviolet photodetectors because it does not exist on the surface of the earth due to the strong absorption of deep ultraviolet light by stratospheric ozone.…”