High-Performance Flexible GaAs Nanofilm UV Photodetectors

Flexible ultraviolet (UV) photodetectors have attractedextensiveresearch interest due to their potential applications in personalUV monitoring, UV electronic eye, anti-UV gloves, and other wearablesystems. In this study, we present a highly sensitive flexible UVphotodetector based on an ultrathin GaAs layer that is produced usinga metal-organic chemical vapor deposition method and epitaxiallift-off film transfer technology. Device performance analysis revealsthat the photodetectors made of a 50 nm thick GaAs layer have excellentsensitivity to 365 nm light. Specifically, the responsivity, specificdetectivity, and external quantum efficiency could reach as high as99.01 A W-1, 1.51 x 10(12) Jones,and 3.37 x 10(4)%, respectively, at -2 V biasvoltage, which are comparable to many UV photodetectors made fromconventional wide band gap semiconductors. Such outstanding UV responseproperties are related to the very high absorption coefficient forUV light and carrier mobility of an ultrathin GaAs film. Equally importantly,the mechanical flexibility resulting from reducing the film thicknessallows the device to maintain its photoelectric properties even aftermore than 500 bending cycles. The totality of these results suggeststhat our flexible UV photodetectors have strong potential applicationsin future wearable devices.