| Summary: | 碩士 === 聖約翰科技大學 === 電子工程系碩士班 === 98 === In this thesis, we reported on the patternable graded porous silicon (PS) membrane by using a novel aodization electrochemical etching apparatus. Four types of shelter patterns including circular, triangle, square and multi-circular were adopted to develop the novel apparatus structure and investigate related effects on PS. The measurements of Maple-PL and scanning electro microscopy (SEM) were utilized to analyze the photoluminescence (PL) property and surface structure of studied PS samples in detail.
Firstly, the graded-PS investigation was started with shelter apparatus. Compared with normal PS sample, the carrier induced graded profile (CIGP) effect was observed from studied graded sample due to the electrolyte current disturbance of adopted shelter. A graded PL property (graded from green to orange-red light region) was obtained. It is noted that the height parameter of adopted shelter (between the shelter bottom and silicon wafer) was the key point to control the graded effect on PS sample. Experimental results indicate that the lower the height parameter is, the obvious the graded PS formation is.
On the other hand, a patternable PS membrane was obtained with changing shelter pattern (such as circular, triangle, square and multi-circular pattern). Corresponding with the above results of CIGP effect, a uniform PS formation was also obtained with increasing in height value. In order to clarify the carrier distribution effect of electrochemical etching current, a locally small anode (copper electrode) was presented to create an accumulative etching current. A graded PS membrane with local electropolishing structure was observed. The surface polish is believed to the carrier accumulation does.
However, the gradual formation is still performed owing to the fringing effect of etching carrier. According to the above results, an outside local anode was finally developed to study the graded relationship between etching carrier path and distribution. With removing the anode form reaction region to outside area, another type of carrier disturbance on studied PS sample has been performed, and therefore the further influence of carrier effect on PS membrane also clarified.
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