The Reseach On Radiation-Damage-Noise Test Sample Of Silicon Substrate Material

Silicon semiconductor is the main substrate material, the properties and the radiation effects have been researched for more than 50 years. But there are certain limitations in existing methods, so we have an urgent need for a sensitive, rapid, nondestructive research tools. Low-frequency noise has the advantage and can be widely used as the diagnostic tool for quality of semiconductor material and device. Low-frequency noise can also be used in the life prediction of semiconductor device.In this thesis, in low dose gamma irradiation, a research on the radiation effect of mono-crystalline silicon solar cell is performed. In mono-crystalline silicon solar cell, the silicon substrate is the base of the device. Electrical parameters and low-frequency noise parameters were measured before and after the radiation. Through measuring and analyzing, it has been found that there is a strong correlation between the radiation damage of substrate material and the quality of the cells. The electric parameter is mainly reflected in the photocurrent decreases and increase of dark current. The degradation of minority carrier lifetime in the base could be account for the effect. The noise parameters are closely related to the barrier zone and mainly reflected in the noise amplitude. The results of the experiment also show that there is a strong correlation between the low frequency noise characteristics and electrical parameters, which implies that the former could be used as a new diagnostic tool for the quality of silicon solar cell. Both the electric model and noise characterization model of the radiation damage of silicon substrate material are proposed.So far, the 1/f noise theory and model is not the same, but built on two major mechanisms. One is the carrier fluctuation mechanism, and the other is the mobility fluctuation mechanism. Carrier fluctuation model can be account for the radiation effects of mono-crystalline silicon solar cell. In order to investigate the mobility fluctuation mechanism, substrate resistance structure is designed. Through theoretical analysis, we've found that there is a strong correlation between the low frequency noise and the substrate doping and geometric parameters. With following experiments, the theoretical model and the designing structure will be verified.