Fig. 2: Crystallographic structure characteristics of multilayer γ-InSe nanoflake.

a Schematic of the two-terminal multilayer γ-InSe-based opto-sensor. Inset: the optical microscopy image of the device. Scale bar: 20 μm. b Left panel: HR-TEM image of the multilayer γ-InSe nanoflake. Right panel: corresponding SAED image. c XRD pattern, d Raman spectra, and e angle dependence of SHG intensity and fitted curves of the prepared γ-InSe nanoflake