TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The silicon nanowire array is prepared by cleaning silicon wafer, placing the silicon wafer face up in hydrofluoric acid/silver nitrate aqueous solution for constant-temperature etching, then taking out and immersing in hydrochloric acid/nitric acid/water, then cleaning with deionized water to obtain the silicon nanowire array with controllable diameter, length and density, which is regularly arranged. The method comprises cleaning the silicon wafer with toluene, acetone and ethanol, then carrying out ultrasonic cleaning using sulfuric acid/hydrogen peroxide and ammonium hydroxide/hydrogen peroxide/water, and then washing a sample reagent with deionized water before or after cleaning. The zinc oxide film deposition process comprises using magnetron sputtering method for depositing zinc oxide film by depositing silicon nanowire on the surface layer of zinc oxide thin film to obtain zinc oxide target material, where the vacuum pressure is less than or equal to 1.7 mPa, sputtering rate 3 nm/minute, and then carrying out rapid thermal annealing process on the resulting sample at 300-500 degrees C for 20-30 minutes. In the step (iii), growing the prepared zinc oxide nanowire using hydrothermal method, placing the silicon nanowire on Teflon (RTM: Polytetrafluoroethylene liner) tray, then placing in an aqueous solution of zinc acetate dihydrate/hexamethylenetetramine to hydrothermally grow silicon substrate perpendicular to the surface, taking out the substrate, and then washing with deionized water for 3 times to obtain the dendritic silicon/zinc oxide hetero-junction nanowire array. Preferred Components: The volume ratio of sulfuric acid and hydrogen peroxide is 3:1. The volume ratio of ammonium hydroxide, hydrogen peroxide and water is 1:1:5. The concentration of hydrogen peroxide is 30 wt.%, and the concentration of ammonium hydroxide is 28 wt.%. The mol concentration of hydrofluoric acid/silver nitrate aqueous solution is 5.25/0.02 mol/l. The constant temperature is 20-30 degrees C. The volume ratio of hydrochloric acid/nitric acid/water is 1:1:1. The concentration of hydrochloric acid is 38 wt.%, and the concentration of nitric acid is 68 wt.%. The thermal growth condition is 90 degrees C, and the mol concentration ratio of zinc acetate dihydrate/hexamethylenetetramine is 25/25 mmol/l.