High-Performance Flexible GaAs Nanofilm UV Photodetectors

Abstract

Flexible ultraviolet (UV) photodetectors have attracted extensive research interest due to their potential applications in personal UV monitoring, UV electronic eye, anti-UV gloves, and other wearable systems. In this study, we present a highly sensitive flexible UV photodetector based on an ultrathin GaAs layer that is produced using a metal−organic chemical vapor deposition method and epitaxial lift-off film transfer technology. Device performance analysis reveals that the photodetectors made of a 50 nm thick GaAs layer have excellent sensitivity to 365 nm light. Specifically, the responsivity, specific detectivity, and external quantum efficiency could reach as high as 99.01 A W −1 , 1.51 × 10 12 Jones, and 3.37 × 10 4 %, respectively, at −2 V bias voltage, which are comparable to many UV photodetectors made from conventional wide band gap semiconductors. Such outstanding UV response properties are related to the very high absorption coefficient for UV light and carrier mobility of an ultrathin GaAs film. Equally importantly, the mechanical flexibility resulting from reducing the film thickness allows the device to maintain its photoelectric properties even after more than 500 bending cycles. The totality of these results suggests that our flexible UV photodetectors have strong potential applications in future wearable devices.

Demonstration of a 3D-Assembled Dual-Mode Photodetector Based on Tubular Graphene/III–V Semiconductors Heterostructure and Coplanar Three Electrodes

“…Photogenerated electron–hole pairs in GaAs/InGaAs heterojunction will fully and immediately recombine as one type of carrier cannot cross over GaAs/InGaAs interface due to the energy gap discontinuity, thus making no contribution to the photocurrent. The spectral response curve of 3DdmPD working at photodiode mode with zero bias is presented in Figure c and indicates that 3DdmPD holds a very broad photoresponse across the UV–vis–NIR spectrum range; however, spectral response becomes very weak beyond 800 nm, which is also reported similarly by other GaAs-based photodetectors, the primary reason lying in the fact that ultrathin rolled-up GaAs has very weak absorption capability to NIR component approaching its cutting-off wavelength (∼870 nm); meanwhile, the rolled-up InGaAs layer although with narrower band gap cannot redshift the spectral response curve according to the above analysis of band gap diagram. Moreover, I – V curves under variable intensity 532 nm green laser irradiation are illustrated in Figure d, where a photovoltaic effect is distinctly observed and the forward photocurrent is generated when a maximum open-circuit voltage ( V OC ) of approximately 210 mV is reached, further confirming that 3DdmPD working at the photodiode mode can be used as a self-driven photodetector (i.e., photodetector with zero bias) in several energy-saving scenarios.…”

III–V Thin Films for Flexible, Cost-Effective, and Emerging Applications in Optoelectronics and Photonics

“…20-layer MELO is assumed in the estimates. (a,c,d,e) Reprinted with permission from ref . Copyright 2023 American Chemical Society.…”

“…One intriguing yet nascent research field is nanofilms (thickness <100 nm), where the film properties differ from the bulk due to the pronounced surface area, and due to the substantially reduced optical thickness. The pronounced surface area makes the nanofilms promising candidates for various concepts often envisioned for nanowires, including sensors that rely on surface reactions. , The minimal optical thickness on the other hand enables e.g., novel photodetector architectures, where the absorption spectrum is decoupled from the band gap . In terms of cost, nanofilms would have great synergy with the MELO process described above as the MELO cost benefits increase as the film thickness decreases.…”

Ultrasensitive photodetector based on 2D WS2/AgInGaS quantum dots heterojunction with interfacial charge transfer

“…Ultrasensitive photodetectors have attracted great research interest in optical memory, photonic nociceptor, imagery and biosensing [1][2][3][4][5][6][7][8]. However, state-of-the-art commercial photodetectors, such as HgCdTe, quantum-well and quantum-dots (QDs) structures, suffer from complex manufacturing processes, high-cost and low working temperature [9].…”