Preparation Of Black Silicon By Metal-Assisted Chemical Etching And Its Photoelectric Properties

Due to the performance limitations of the single crystal silicon material,the light reflectance of silicon in the visible-near-infrared band is very high,which limits the key properties of the application range,sensitivity and conversion efficiency of the silicon-based material.Black silicon is a new type of semiconductor material.Due to the surface microstructure of its pores or sharp cones,the surface roughness is large,which greatly increases the light absorption rate in the visible-near-infrared region and greatly improves the photoelectricity of materials.Conversion efficiency has broad application prospects for photodetectors,photodiodes,solar cells,field emitters and other optoelectronic devices.At this stage,there are many preparation methods of black silicon,but the metal-assisted chemical etching to prepare black silicon has the advantages of simple operation,low cost,and large-scale operation,which provides a possibility for the commercialization of black silicon.In this paper,the effects of silver nitrate solution concentration,etching time and etching temperature on the morphology and light absorptivity of black silicon samples prepared by metal-assisted chemical etching in black silicon were studied,and the prepared black silicon samples were prepared.The surface of the interdigital electrode was prepared to study the photoelectric properties of the sample such as light and dark current,quantum efficiency and sensitivity.According to the research in this paper,when the concentration of silver nitrate solution increases from 0.01 mol/L to 0.03 mol/L during the process of metal-assisted chemical etching,the silver particles aggregate due to the increase of the concentration of silver particles in the solution during deposition.The etched hole structure changes from a single structure to an aggregate structure,the average depth is increased from 4 ?m to 6 ?m,and the average light absorption rate in the wavelength range of 200-1000 nm is increased from 50% to 65%;When increasing from 30 min to 45 min,the size of the etched holes is around 100 nm,the average depth is increased from 4 ?m to 9 ?m,and the average light absorption rate is increased from 50% to 90% in the wavelength range of 200-1000 nm.When the etching temperature is increased from room temperature to 70 ° C,the etched pore structure is around 100 nm,and the average depth is increased from 3 ?m to 8 ?m.When the light absorption of the sample increased from 25% to 85,the sensitivity of the sample increased from 0.0037 A/W to 0.00847 A/W,and the quantum efficiency increased from 0.782% to 1.9%.For samples with an average light absorptivity of 85% in the wavelength range of 200-1000 nm,when the reverse bias voltage of 1 V to 5 V is applied,the dark current of the sample increases by 7.9 ?A and no longer increases with the increase of the bias voltage.When it is increased to 0.0824 A/W,it does not change significantly with the increase of the bias voltage,and the quantum efficiency increases to 18.56% without increasing with the increase of the bias voltage.