Optical Characteristics Of Doped-silicon Nano-structures And Their Applications

Photodetectors are an essential component in optoelectronic detecting system, we utilize them convert optical signal to electronic signal. As one kind of typical photodetectors, semiconductor detectors have been widely applied in security and livelihood. With the progress of technologies of integrated circuits, semiconductor photodetectors, especially silicon-based devices, have made great breakthroughs in miniaturization, integration and low-cost. Silicon-based photodetectors would still be one of the most valuable devices to investigate and develop in the future. Thus study of silicon-based novel photodetectors is of great value.In this thesis, several studies of principle and technologies involving phototransistive gain enhanced, glimmer detector based on doped silicon nanostructure and infrared detector based on localized plasmon resonances in mid-infrared are presented as follow:(1) The principle of creating a very high photoelectronic gain has been analyzed. Some concepts about surface states, energy bending and built-in electric field, which greatly affects the properties of devices, have been explained. Device model for simulation is established, and the device response at low-level light illumination is simulated and optimization of several factors including doping concentration, physical dimension and surface state density has been done. In order to overcome the poor controllability during the fabrication, we have proposed a PN junction instead of built-in electric field formed by surface states. The results of simulation reveal that the PN junction structure of gain almost up to 106. The value of gain has no longer relevant to surface states.(2) The principle of enhanced absorption by localized surface plasmon resonances has been analyzed. Photothermal characteristics of nanostructure and PN junction have been introduced and investigated. The influence of some parameters including diameter, doping concentration, polarization, substrate material and environment medium on the optical characteristics is considered.(3) A brief introduction of the structure and manufacturing flow of device is presented. Both of electron beam lithography and inductively coupled plasma etch have been used in fabrication. Process parameters of device are explored to lay a solid foundation for continuing and improving the device.