Self‐Powered and Spectrally Distinctive Nanoporous Ga₂O₃/GaN Epitaxial Heterojunction UV Photodetectors

Abstract

Herein, self‐powered spectrally distinctive UV photodetectors (PDs) based on nanoporous epitaxial Ga2O3/GaN heterojunctions grown by metalorganic chemical vapor deposition (MOCVD) are reported. The nanoporous structures are formed by a novel self‐reactive etching (SRE) method, which significantly enhances the device performance. PDs with different porosities are fabricated and compared. In the self‐powered mode, the PD with the highest nanopore porosity exhibits the best performance, with an ultralow dark current of 0.04 nA, a fast photoresponse speed, and a high responsivity of 43.9 mA W−1 (35.8 mA W−1) under 254 nm (365 nm) illumination, which is 800% higher than that of the reference device without the porous structure. Furthermore, opposite current polarities are observed in the PDs under different illumination spectra, the mechanism of which is explained by the carrier transportation using the device band diagrams. This phenomenon can be used to distinguish different incident spectra, opening the door to more new applications. This work represents one of the first spectrally distinctive self‐powered UV PDs based on nanoporous Ga2O3/GaN heterojunctions and significantly benefits the development of multifunctional UV PDs.

Ga2O3/GaN Heterointerface-Based Self-Driven Broad-Band Ultraviolet Photodetectors with High Responsivity

“…Figure c shows the top-view image of FESEM measurement, where the surface morphology of the film reveals asymmetrically distributed Ga 2 O 3 nanogranules (NGs) with an average size of ∼97 nm. These NGs have a larger effective surface area, which boosts light absorption and enhances photocurrent, making them suitable for BBUV photodetection devices. , The thickness of the thermally oxidized Ga 2 O 3 layer and the GaN layer was determined by a cross-sectional FESEM image (Figure d) and found to be ∼700 nm and ∼3.4 μm, respectively. The energy-dispersive X-ray analysis (EDAX) maps of Ga, N, and O before and after thermal oxidation of epitaxial GaN film are given in Figure S1, Supporting Information (SI).…”

Structural designs of AlGaN/GaN nanowire-based photoelectrochemical photodetectors: carrier transport regulation in GaN segment as current flow hub

“… – 29 For example, Li et al. and Chen et al 25 , 26 . reported the PDs with Ga2O3 and p-GaN segments, indicating the bipolar photoresponse under 254 and 365 nm illuminations.…”

“…Although the solid-state dual-spectral PDs (including types of the p–n junction and metal modification) have been demonstrated, the photocurrents of spectrum-distinguishable devices are too low 25 – 29 For example, Li et al. and Chen et al 25 , 26 .…”

Observation of polarity-switchable photoconductivity in III-nitride/MoSx core-shell nanowires

“…In this article, we combine earth-abundant molybdenum sulfides with the popular group III-nitride semiconductor nanowires to construct a spectrally distinctive photoelectrochemical photodetector with high photoresponse and excellent tunability. Essentially, the pursuit of polarity-switchable photoconductivity behavior has recently attracted considerable interests [35][36][37] , because the polarity-switchable photocurrent can be employed to distinguish spectrum bands while measuring corresponding light intensity, which has been realized in many solid-state devices [37][38][39][40] . The proposed III-nitride/a-MoS x core-shell nanostructures demonstrate a polarityswitchable photoconductivity under different-energy photon illumination, i.e., it exhibits a polarity-switchable photoresponse with a responsivity of −100.42 mA W −1 under 254 nm illumination, and 29.5 mA W −1 under 365 nm illumination, one of the highest value among reported polarity-switchable devices 36,[38][39][40][41][42][43][44][45][46][47][48][49][50] .…”

“…Essentially, the pursuit of polarity-switchable photoconductivity behavior has recently attracted considerable interests [35][36][37] , because the polarity-switchable photocurrent can be employed to distinguish spectrum bands while measuring corresponding light intensity, which has been realized in many solid-state devices [37][38][39][40] . The proposed III-nitride/a-MoS x core-shell nanostructures demonstrate a polarityswitchable photoconductivity under different-energy photon illumination, i.e., it exhibits a polarity-switchable photoresponse with a responsivity of −100.42 mA W −1 under 254 nm illumination, and 29.5 mA W −1 under 365 nm illumination, one of the highest value among reported polarity-switchable devices 36,[38][39][40][41][42][43][44][45][46][47][48][49][50] . Moreover, the underlying mechanism of polarity-switchable photoconductivity behavior is revealed via density functional theory (DFT) calculations.…”