UV photodetector based on energy bandgap shifted hexagonal boron nitride nanosheets for high-temperature environments

We extend our investigations in the use of boron nitride nanosheets (BNNSs) as sensing material for UV photodetectors by exploring the energy bandgap shift in a new BNNSs arrangement on silicon substrate produced by a pulsed laser plasma deposition (PLPD) technique. Characterizations by XRD and Raman spectrum analysis indicate that the material is composed of high purity hexagonal boron nitride (hBN). SEM and AFM images confirm this particular arrangement of BNNSs is made of randomly orientated hBN nanosheets. The BNNS on silicon substrate material exhibits higher conductivity and photosensitivity in deep UV region than previously investigated BNNS thin films. The material is also sensitive to the UVB region, indicative of having a lower band gap width than that of bulk or thin films, while remaining visible-blind. The observed decrease in cut-off frequency was a direct result of the structural arrangement of the BNNSs in the film. This has the advantage of avoiding doping in order to tune bandgap width, which can compromise intrinsic desirable properties of hBN. Additionally, the material performed extremely well as a UV photodetector even at temperatures as high as 400 °C, making this particular arrangement of BNNSs an ideal candidate for applications where UV sensing in high-temperature environments is required. (paper)