Enhanced photoresponse performance in Ga/Ga2O3 nanocomposite solar-blind ultraviolet photodetectors**Project supported by the National Natural Science Foundation of China (Grant Nos. 11674405 and 11675280) and the Fund from the Laboratory of Microfabrication in Institute of Physics, Chinese Academy of Sciences.

Abstract

In the present work, we explore the solar-blind ultraviolet (UV) photodetectors (PDs) with enhanced photoresponse, fabricated on Ga/Ga2O3 nanocomposite films. Through pre-burying metal Ga layers and thermally post-annealing the laminated Ga2O3/Ga/Ga2O3 structures, Ga/Ga2O3 nanocomposite films incorporated with Ga nanospheres are obtained. For the prototype PD, it is found that the photocurrent and photoresponsivity will first increase and then decrease monotonically with the thickness of the pre-buried Ga layer increasing. Each of all PDs shows a spectrum response peak at 260 nm, demonstrating the ability to detect solar-blind UV light. Adjustable photoresponse enhancement factors are achieved by means of the surface plasmon in the nanocomposite films. The PD with a 20 nm thick Ga interlayer exhibits the best solar-blind UV photoresponse characteristics with an extremely low dark current of 8.52 pA at 10-V bias, a very high light-to-dark ratio of ∼ 8 × 105, a large photoresponsivity of 2.85 A/W at 15-V bias, and a maximum enhancement factor of ∼ 220. Our research provides a simple and practical route to high performance solar-blind UV PDs and potential applications in the field of optoelectronics.