Black Silicon Preparation Technology And Photoelectric Characteristics Research

As a new semiconductor material, black silicon has excellent optical and electrical properties. Black silicon’s surface microstructure is columnar forest, and thus has a high absorption rate to light. It can absorb the light between near ultraviolet and infrared, with an absorption rate up to90%. It has broad prospects in photodetectors and solar cells. Compared to silicon solar power film, solar power film produced by black silicon can increase its power generation efficiency as much as300times, so black silicon’s discovery offers a new way to solve the global energy crisis. Black silicon technology can be well cooperated with modern MEMS technology, makes the structure, photovoltaic systems miniaturization, integration and intelligencer realized. As a result it is an important field for modern photoelectric detectors research. The contents of the thesis including the following aspects:Using wet etching method to make a good layer morphology of the black silicon layer. This method is simple and needs less equipment, we make finish the black silicon product in a simple chemical laboratory and the black silicon’s surface looks excellent, the pore size is50-80nm with a depth up to500nm.Electrode aluminum film of the black silicon surface is prepared by vapor deposition method, MEMS technology is used to get lithography preparation MSM structure of the electrode, both the electrode width and spacing are5μm. The photocurrent of the preparing black silicon MSM photodetector can be up to129.9μA.According to MSM optoelectronic photodetector performance analysis to black silicon with different Si3N4barrier layer thickness, we can conclude that: Among30nm,60nm,90nm,(Si3N4barrier layer’s thickness) the optimum thickness for the black silicon photodetector is30nm.When the barrier layer thickness is30nm and bias voltage is4V, the photoelectric sensitivity is0.274A/W and signal to noise ratio is28.7dB.Explore the annealing’effect on the optical and electrical properties of the black silicon and found that annealing can improve the optical and electrical properties of black silicon, the reason is that the heat treatment makes the point defect redistribution and black silicon-silicon at the interface between the space re-build, so the device transmission performance has been improved. On the other hand, rapid thermal annealing of high heating and cooling rate, annealing can deal with the release of material’s tensile stress, reducing the density of dangling bonds.Finally, the paper also briefly explores the black silicon dry etching method, also gives a simple analysis of its morphology.