| Summary: | 碩士 === 國立中央大學 === 電機工程研究所 === 97 === This thesis demonstrates that controlling the position and the number of Ge quantum dots (QDs) embedded in SiO2 or Si3N4 tunnel barriers in a self-organized manner is realized by oxidizing SiGe nano-trenches. A single Ge QD in the core or double QDs at the edges of oxidized SiGe trenches could be effectively modulated by the trench geometry and the materials adopted for spacer and bottom layers. For SiGe trenches with SiO2 spacers having an trench width of less than 30 nm, Ge QDs line up in the center of oxidized trenches with an average dot size of 12.5 ± 2.8 nm. In contrast, for SiGe trenches with Si3N4 spacers having the same trench width, smaller Ge QDs (9.7 ±?1.5 nm) reside randomly either in the center or near the edges of oxidized trenches. For SiGe trenches with width of 50 or 70 nm, we observed remarkable twin Ge QDs precipitation closely along each boundary between the trench and the nearby SiO2 and Si3N4 spacers, respectively, with an average dot size of 11.4 ± ?0.9 nm and 8.3 ±?1.4 nm. Using this method, it is reasonable to expect that effective single-electron transistors and coupled QD devices could be realized.
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