| Due to the prominent characteristic and novel physical effect, nano-structures of metal-semiconductor have broad application prospects in the field of high-tech such as energy, aerospace, biology and information. In the past 10 years, a lot of reports have demonstrated that nano materials have more outstanding photoelectric performance than bulk materials, empowering fabrication method and discovery of novel photoelectric effect one of the frontier topics. The thesis is an exploratory research focusing on this topic. By studying the photoelectric effects(including lateral photovoltaic effect(LPE), light-induced resistance effect and light-modulated resistance switching effect) on various nano-materials, our motivation is to discover novel effects, reveal the new physical mechanism and finally obtain photoelectric materials or sensors with practical value and external field(light) modulation feature. The materials studied in this thesis are nano structure of metal-oxide-semiconductor(MOS), including nano films, Cd Se quantum dots(QDs) and Si O2 colloidal crystals(CCs).The main results of LPE observed in the various MOS structures are as follows: in the structure of Ti/Ti O2/Si, the obtained LPE sensitivity of 169 m V/mm represents currently the highest level compared to previous reported results(~20m V/mm); we refine the photon-generated carrier diffusion mechanism based on observed relationship between LPE sensitivity and resistance property of samples under dark condition in the structure of Cr/Si O2/Si; a QDs enhancement LPE is observed in the structure of Zn/Cd Se QDs/Si for the first time, which enriches the applications of QDs in photoelectric devices; we also obtained LPE in the structure of Au/Si O2(CCs)/Si with a maximum sensitivity of 86 m V/mm, about 5 times of that obtained in the nano film of Au/Si O2/Si.Light response of resistance in nano-materials is another research focus in this dissertation. We observed light-induced polar resistance effect in the structure of Zn/Cd Se QDs/Si: the change rate is as high as 280% which is much higher than that obtained in Zn/Si nano-film structure(only 15%). And we also observed a type of light-modulated resistance switching effect on silicon-based Au films covered CCs, where resistance hardly changes with applied voltage under dark condition; in contrast, the positive voltage sweep can switch the structure from a high resistance state to a low resistance state, which is a novel phenomenon resulting from interactions between light and external electric field. |
