GaAs Nanowire Array Cathode Prepared On Substrate Covered With SiO₂ Nanospheres

The GaAs nanowire array structure has both the fundamental properties of GaAs and the peculiar properties of nanomaterials,making the prepared negative electron affinity?NEA?photocathode has the advantages of high quantum efficiency and low dark current.Thus,the NEA GaAs photocathode has become one of the most promising photoelectric emission materials,and it will have a wide range of applications in high-performance electron source,photomultiplier tube,solar cells and other fields.In this paper,based on the photoelectric emission model,I simulated and analyzed the influence of GaAs nanowires array photocathode for different incident conditions such as incident angle,nanowire diameter,nanowire height and nanowire spacing?ie D/P?.According to the simulation results,the GaAs nanowire array was prepared by colloid etching method,and the experimental steps and parameters were improved in the preparation process.In this paper,the SiO₂ nanospheres with diameter of 350 nm and 500 nm were synthesized by the modified Stober method.The synthesized SiO₂ nanospheres were spin-coated with 600 rpm for 10 seconds and then passed at 1900 rpm for 4 seconds.The mask is relatively ideal,and finally the GaAs substrate is etched with a nanospheric mask layer to prepare a GaAs nanowire array.The influence of etching time,etching power and etching gas on the nanowire array was analyzed by SEM.The relationship between the etching time and the etching depth was found.The linear relationship was obtained by using the step profiler,AFM and diffuse reflectance spectrometer.Finally,The Cs-F alternating activation experiments were performed on the prepared GaAs nanowire arrays to form a negative electron affinity cathode,and the quantum yield test of the final prepared GaAs nanowire array photocathode was carried out.The GaAs nanowire array structure has a quantum efficiency of at least 50% higher than that of a GaAs substrate,confirming that the photoemission efficiency of the nanowire array structure is high.