Nanoscale structure study of boron nitride nanosheets and development of a deep-UV photo-detector.

In this communication, we report on the synthesis of few atomic-layer boron nitride nanosheets (BNNSs) and their application for deep ultraviolet photo-detection. Synthesis of BNNSs is carried out by using the short-pulse plasma beam deposition technique. High-resolution tunneling electron microscopy, cathodoluminescence spectroscopy and photo-stimulated measurements are conducted and linked to characterize the BNNS morphology. The obtained BNNSs are flat with a typical size of 50 × 50 μm(2) and are optically transparent down to 210 nm. Nanoscale studies by transmission electron microscopy revealed that these nanosheets are composed of a densely packed honeycomb crystal lattice structure of covalently bonded boron and nitrogen atoms. Cathodoluminescence spectroscopy of these nanosheets revealed a single sharp excitonic peak centered at 233 nm at 300 K. The synthesized BNNSs are used to demonstrate applicability of BNNSs for detecting ultraviolet photons. The initial experimental tests of the developed prototype BNNSs based deep-ultraviolet photo-detector show that it is blind to photons with an energy less than 4 eV. The calculated output power of the detector is approximately 2 μW and the ratio between the output electrical power and the input optical power is ∼1%.