Growth and Analysis of Group IV Semiconductor Nanowires
Date Issued
2014
Date
2014
Author(s)
Tsai, Yun-Yi
Abstract
Group IV semiconductor materials such as silicon and germanium are potential candidates for future applications in high performance semiconductor devices by means of nanowire structure. Defects due to lattice mismatch between Si and Ge at Si-Ge heterojunction interface can be avoided as well when the heterojunction is made into nanowire structure. In order to realize these applications, the morphology and interior composition distribution must be controlled precisely. In this study, we grew Si nanowires and SiGe alloy nanowires via vapor-liquid-solid (VLS) mechanism and grew heterojunction structure nanowires via vapor-solid-solid (VSS) mechanism in a chemical vapor deposition (CVD) reactor. The correlation between nanowire growth and growth factors such as catalysts, gas precursors, temperature, pressure, and cleanness was discussed based on our experimental results. In SiGe alloy nanowires, the amount of Ge would affect the transport properties of nanowires, so it is important to control and measure the Ge content in nanowires. Common surface analysis techniques are difficult to get accurate composition due to the small diameter of nanowires. Thus, we performed quantitative analysis of SiGe alloy nanowires by using energy dispersive spectroscopy (EDS) in scanning transmission electron microscopy (STEM). Four SiGe films with different compositions were served as standards in EDS analysis. The results of quantitative analysis showed that the amount of Ge increases as a nonlinear function of partial pressure of gas precursors, and the chemical reactivity of gas precursors is the key to control the nanowire interior composition. In Si-Ge heterojunction growth, controlling the composition distribution at interface precisely is helpful for fabricating desired electronic devices. For this purpose, we grew nanowires via VSS mechanism and finally fabricated heterojunction nanowires by using a mixture of Ag and Au as catalysts (AgAu). The interface width of Si-Ge heterojunction is only few nanometers.
Subjects
矽
鍺
氣相液相固相機制
氣相固相固相機制
奈米線
異質介面
穿透式電子顯微鏡
Type
thesis
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