Construction of organic/GaN heterostructures for DUV-to-NIR broadband photodetection.

Herein, a broadband photodetector (BPD) is constructed with consistent and stable detection abilities for deep ultraviolet to near-infrared spectral range. The BPD integrates the GaN template with a hybrid organic semiconductor, PM6:Y6, via the spin-coating process, and is fabricated in the form of asymmetric metal-semiconductor-metal structure. Under an optimal voltage, the device shows consistent photoresponse within 254 to 850 nm, featuring high responsivity (10 to 60 A/W), photo-to-dark-current ratio over 103, and fast response time. These results show the potential of such organic/GaN heterojunctions as a simple and effective strategy to build BPDs for a reliable photo-sensing application in the future.

AlGaN-based Schottky barrier deep ultraviolet photodetector grown on Si substrate.

This letter reports the influence of material quality and device processing on the performance of AlGaN-based Schottky barrier deep ultraviolet photodetectors grown on Si substrates. The thermal annealing can significantly improve Schottky barrier height and wet chemical etching can effectively remove etching damage. Meanwhile, the decrease of threading dislocation density and the pit size, especially the later, can substantially suppress reverse leakage. As a result, the reverse leakage current density of the as-fabricated deep UV photodetector was reduced down to 3×10-8 A/cm2. Furthermore, the responsivity of the deep UV photodetectors was greatly improved by reducing the point defect concentration.

AlGaN/GaN-based Photoimaging Transistors and Arrays with Reconfigurable Triple-Mode Functionalities Enabled by Voltage-Programmed Two-Dimensional Electron Gas.

High-quality imaging units are indispensable in modern optoelectronic systems for accurate recognition and processing of optical information. To fulfill massive and complex imaging tasks in digital age, devices with remarkable photoresponsive characteristics and versatile reconfigurable functions on a single device platform are in demand but remain challenging to fabricate. We report an AlGaN/GaN-based double-heterostructure, incorporated with a unique compositionally graded AlGaN structure to generate a channel of polarization-induced two-dimensional electrons that can be modulated to control electron separation, collection, and storage process in the channel of the fabricated phototransistor. As a result, when exposed to different light sources, the device shows reconfigurable multifunctional photoresponsive behaviors with superior characteristics owing to the successful programming of the 2DEGs by the combined gate and drain voltage inputs. A self-powered mode with a responsivity over 100 A/W and a photoconductive mode with a responsivity of ∼108 A/W were achieved, with the ultimate demonstration of a 10×10 device array for imaging. More intriguingly, the device can be switched to photoelectric synapse mode, emulating synaptic functions to denoise the imaging process while prolonging the image storage capability. Demonstrating three-in-one operational characteristics in a single device offers a new path toward future integrated and multifunctional imaging units. This article is protected by copyright. All rights reserved.

High Performance of Zero-Power-Consumption MOCVD-Grown ß-Ga2O3-Based Solar-Blind Photodetectors with Ultralow Dark Current and High-Temperature Functionalities.

In this article, we report on high-performance deep ultraviolet photodetectors (DUV PDs) fabricated on metal-organic chemical vapor deposition (MOCVD)-grown ß-Ga2O3 heteroepitaxy that exhibit stable operation up to 125 °C. The fabricated DUV PDs exhibit self-powered behavior with an ultralow dark current of 1.75 fA and a very high photo-to-dark-current ratio (PDCR) of the order of 105 at zero bias and >105 at higher biases of 5 and 10 V, which remains almost constant up to 125 °C. The high responsivity of 6.62 A/W is obtained at 10 V at room temperature (RT) under the weak illumination of 42.86 µW/cm2 of 260 nm wavelength. The detector shows very low noise equivalent power (NEP) of 5.74 × 10-14 and 1.03 × 10-16 W/Hz1/2 and ultrahigh detectivity of 5.51 × 1011 and 3.10 × 1014 Jones at 0 and 5 V, respectively, which shows its high detection sensitivity. The RT UV-visible (260:500 nm) rejection ratios of the order of 103 at zero bias and 105 at 5 V are obtained. These results demonstrate the potential of Ga2O3-based DUV PDs for solar-blind detection applications that require high-temperature robustness.