Fabrication Of Microstructured Silicon And Its Application In PIN Photodetector

Silicon is one of the most abundant semiconductor materials on the earth. It has been widely used in semiconductor devices. It is well know that pure silicon material, as crystal silicon, can be made easily at much lower cost through modern technologies, and the associated technology has come of age. Owing to its large band gap, crystal silicon can’t absorb light with longer wavelength effectively. What’s more, the crystal silicon has a high reflectivity in the range of visible light, so it can’t fully meet the requirement in photovoltaic or other areas. With the discovery of “black silicon”, many microstructured silicon materials with unique performance have caused widespread concern. The common feature of such silicon materials is that all of them have much more uniform light trapping centers. This unique structure allows multiple reflection of incident light on its inclined surface.In order to have a deep understanding on the fabrication of microstructured silicon, and to give an attempt in the actual manufacturing of new PIN photodetector based on the microstructured silicon, this paper has carried out many studies by electrochemical etching and nanoimprint lithograph. The metal/semiconductor contact quality is a critical factor in the manufacturing of semiconductor devices. In order to prepare a high quality metal/semiconductor contact in the surface of microstructured silicon, this paper has studied traditional physical vapor deposition, electroless plating and chemically modifying before vapor deposition, comparatively. The results of SEM and I-V characteristics test indicate that traditional physical vapor deposition is hardly applied in making qualified electrodes on the surface of microtructured silicon, while electroless plating and chemically modifying before vapor deposition can be used to make electrodes with ohmic contact perfectly.Furthermore, we have tried to develop a new type of PIN photodetector based on porous silicon, and carried out an actual manufacture through a foundry. Our preliminary studies indicate that the responsivity of the new PIN photodetector based on microstructured silicon has been obviously improved in the range of visible to near infrared light(300 nm~1100nm). Moreover, we have also tried to develop a new type of PIN photodetector based on microstructurd silicon.