Gan-Based Hemt-Type Multi-Functional Phototransistors

Photoelectric detection technology is key in the field of modern (opto-)electronic systems. It can convert optical signals into electrical signals, thereby achieving the perception, detection, and processing of various optical information. To accomplish large-scale and complex imaging tasks in multiple fields in the digital era, devices that possess significant light response characteristics and multifunctional reconfigurable capabilities on a single platform are required, yet fabrication remains challenging. In this work, we comprehensively explored the optoelectronic properties of GaN-based HEMT (high-electron-mobility transistor) platform and managed to reconfigure the device structures towards multi-functional highquality photo-imaging arrays. By taking advantages of the high-concentration and high-mobility two-dimensional electron gas (2DEG) at the AlGaN/GaN heterostructures, such devices can cover a broadband ultraviolet (UV) photodetection from vacuum UV to near UV range, achieving ultrahigh static photosensitivity and decent dynamic photoresponse behavior at both room temperature and a high temperature of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$250{ }^{\circ} \mathrm{C}$</tex>. Furthermore, by inserting an additional AlGaN back barrier with decreasingly graded Al profile beneath the conventional <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{AlGaN} / \text{GaN}$</tex> channels, we constructed a double-heterostructure (DH) phototransistor (PT) with exceptional photoelectric imaging. The unique compositionally graded AlGaN back barrier can facilitate improved carrier generation, separation, and confinement in the conductive channel. As a result, a photoconductive mode with a responsivity of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\sim 10^{8} ~\mathrm{A} / \mathrm{W}$</tex> and a self-powered mode with a responsivity of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\sim 100 ~\mathrm{A} / \mathrm{W}$</tex> are achieved. More interestingly, the device can operate in photoelectric synapse mode, simulating synaptic functions to denoise the imaging process while extending image storage capacity. Moreover, a highly compact ultraviolet imaging array with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10 \times 10$</tex> integrated DH-PTs is fabricated, effectively validating the feasibility and advantages of the AlGaN/GaN photoelectric platform for efficient, multifunctional, and single-platform photoelectric systems.