Thermally StableEdge-Functionalized Hexagonal BoronNitride Quantum Dots for Blue Light Photodetector Applications

Quantum dots (QDs) of hexagonal boron nitride (hBN) synthesized by using the bottom-up approach have been characterized. Significant red shift in the band gap of hBN QDs has been observed on functionalization. Due to better functionalizability, these QDs synthesized by the bottom-up method showed superior blue emission (∼20 times) as compared to the ones obtained by the top-down method. The temperature dependence of the PL shows that the QDs are suitable for use in optoelectronic devices. This is due to their low thermal expansion coefficient, direct band gap, and high activation energy. As an application of this study, a photodetector at 405 nm on silicon (Si) substrate using a silver electrode has been demonstrated. The blue light photodetector shows a responsivity of 11 mA/W, external quantum efficiency of 3.4%, and detectivity of 1.5 × 10⁹ Jones. The device with easy fabrication technique exhibits a faster photoresponse, making it suitable for optoelectronic devices.