Ultraviolet Photodetector Based On The Hybrid Graphene/Phosphor Field-Effect Transistor

Recently, a hybrid graphene/poly-BrNpA phosphor structure was used to fabricate rewritable p-n junction photodiode responsive to visible light. In this process, photoisomerization occurred under moderate ultraviolet (UV) irradiation (lambda = 365 nm, optical intensity I-UV = 1.318 mu W mu m(2)), and the subsequent water (H2O) molecule adsorption facilitate charge transfer at the interface. In this study, we explore the feasibility of making UV photodetector based on the hybrid graphene/poly-BrNpA field-effect transistor. The incident UV light (lambda = 365 nm, IUV <= 1.81 x 10(-4) mu W mu m(-2)), which is at least four orders weaker than that used to induce observable photoisomerization in the phosphor, is mostly absorbed to create photo-induced electron-hole pairs. The sub-sequent separation and transfer of the photo-induced electrons to graphene contribute to high photocurrent by the photogating effect. The photodetector has a responsivity and specific detectivity up to 159 A W-1 and 1.55 x 10(11) Jones, respectively, when biased at V-DS = 1 V. The photodetector has a slow response, especially to UV shutoff with the fall time tau(F) up to 881 s. By virtue of H2O molecule adsorption, tau(F) can be reduced to 6.6 s by accelerating the reversion and recombination of electrons with the photo-induced holes trapped in the polyBrNpA film through introducing defect states. This work brings a new perspective for developing photodetectors through combining the functional two-dimensional materials and phosphors.