Fig. 1
From: Widely tunable black phosphorus mid-infrared photodetector
Structure of the tunable BP mid-IR photodetector based on a dual-gate transistor configuration. a, b Schematic (a) and optical (b) images of the dual-gate hBN/BP/hBN FET. Left device in b is used for the electrical and optoelectronic measurements. Scale bar: 10 μm. c The cross-section HR-TEM image of the hBN/BP/hBN stack. The thickness of BP is around 5 nm (10 layers). Right panel is the element analysis image for nitrogen (blue), phosphorus (green), and oxygen (red). Scale bars: 4/10 nm (left/right). d The ratio of Raman A g 2 and A g 1 peak intensity as a function of the excitation laser polarization. The ratio peaks when the excitation laser polarization is aligned along the X-direction (armchair) of BP
