High-efficient ultraviolet (UV) photocathode using optimum radial shaped AlxGa1-xN nanostructure with assisted external electric field

Abstract

Abstract In this paper, we study the influence of the distribution of Al composition, the built-in electric field and the height of the sublayer on the optical and electrical response of the gradient Al composition AlxGa1-xN photocathode. The results show that the electrical response of these nanoarrays mainly depends on the technical parameters such as the structure spacing, incident light angle and distribution of Al composition. In this work, using the spicer three-step emission theoretical model, we systematically analyzed the quantum efficiency and collection efficiency of gradient Al composition AlxGa1-xN nanostructure with different Al composition distributions. Surprisingly, when the photon energy is 4.4eV~6eV and the Al composition is 0 and 0.635, AlxGa1-xN nanostructures with sublayer heights of 300 nm and 200 nm reach optimized quantum efficiency. Taking into account the diffusion movement of the emitted electrons and the re-absorption effect of the sub-wavelength surface, we introduced the assisted external electric field to improve the collection efficiency of the photocathode. When the external electric field is 2.5 V/μm, the spacing is 300 nm and the incident angle is 30°, the variable Al composition nanostructure can achieve an electron collection efficiency of nearly 31.13%. The research methods and results in this paper provide an optimized solution with reference value for the next generation of high-performance UV photodetectors using gradient Al composition AlxGa1-xN nanostructures to improve photoelectric properties of the photocathode.