Preparation And Characterization Of The Black Silicon Materials Research

Silicon, being one of the most abundant elements on the earth, is widely used in light detectors, optical communications, micro-electronic equipments, and other important fields. However, due to the nature of crystalline silicon, its reflectivity for light between visible and infrared is so high that the key technical indicators, e.g. sensitivity, available spectrum range and conversion efficiency, of silicon-based optoelectronic devices are severely diminished. In recent years, a kind of micro-structured silicon– black silicon has drawn great attention. Because of its strong absorption over the band from visible to infrared, black silicon can be widely used in various fields, like biology, infrared detection, solar cells, medicine, microelectronics, agriculture, security check, and so on. At present, there are various ways to prepare black silicon,yet none of them is perfect. This thesis presents a novel method to prepare black silicon by the traditional wet etching technique. Through surface texturized, black silicon material with above 90% absorption from visible to near-infrared band has been obtained. A simple and economically feasible method for the fabrication of black silicon is proposed.The main work and conclusions can be listed as follows:1. Two mask plates with different sizes were designed: one wasφ2μm×2μm and the other wasφ1μm×4μm; and wet-etched mask layers were fabricated by using photoetching technique to transform patterns and reactive ion etching (RIE) technique to etch Si3N4 films.2. Regularly arranged microstructure arrays were fabricated with KOH corrosion system and examined with scanning electron microscope (SEM). The affect of parameters, like KOH concentration, temperature and corrosion time, on microscopic features of samples were studied, and basic experimental parameters and rules to control surface features are concluded.3. Furthermore, microstructure surface was modified by gold particles catalysis with HF corrosion system. 4. Black silicon samples, which were fabricated with KOH corrosion system, were studied by using integrating sphere detector, and absorption properties of samples, surface of which were modified with HF corrosion system, were measured over the wavelength range from 250 nm to 1200 nm. Absorption coefficients of samples, which were fabricated with KOH corrosion system, were above 80% over the visible to near infrared band. Meanwhile,absorptions coefficients of samples, microstructure surface of which were modified with HF corrosion system, were higher than 90% over the visible to near-infrared band.5. Causes and mechanisms of the increased absorption of black silicon microstructure surface are analyzed and concluded.