Fig. 4
a The reflectance of a Gr/Si photodetector before (red) and after (violet) being coated with Al2O3 antireflection over the spectral range of incident light spectra (200–1100 nm). b Microphotographs of the Gr/Si photodetector coated with a 40 nm Al2O3 thin film. c, The J–V characteristics of the photodetector in dark and under illumination by 365 nm UV light before and after Al2O3 coating. d The spectral IPCE and e full spectral responsivity of the photodetector before and after Al2O3 coating. f Zoom-in plot of the UV spectral responsivity for the photodetector D1, D2, D3 and the theoretically attainable maximum responsivity with and without reflection (R) (solid blue and red curves, respectively)
