Selective Growth of RuO2 Nanorods Using Reactive Sputtering

• Main Authors: Wei-te Li, 李威德
• Other Authors: Dah-Shyang Tsai
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/qdf7ra

碩士 === 國立臺灣科技大學 === 化學工程系 === 95 === The technique of area-selective growth of RuO2 nanorods via reactive sputtering is explored in this master thesis. The substrates are sapphire (100) and (012), denoted as SA(100) and SA(012), patterned with SiO2 using a copper grid mask. The RuO2 nanorods are vertically aligned on SA(100), tilted 35�a with respect to the substrate normal on SA(012). Each nanorod is a RuO2 single crystal, confirmed by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). The Ru:O ratio on the surface of sputtered RuO2 nanorods is higher than the stoichiometric 1:2 ratio, measured by X-ray photoelectron spectroscopy. The success of area-selective growth relies on the difference between nucleation barriers on the noncrystalline SiO2 and the sapphire surfaces. RuO2 nucleates with ease on SA(100) and SA(012) surface, but slowly on the noncrystalline SiO2 surface. When the RuO2 clusters constantly diffuse away from the nongrowth area of SiO2 surface, meanwhile nucleate and grow in the growth area of SA(100) or SA(012), a pattern of RuO2 nanorods can be achieved. Our experimentation shows that the optimum conditions for selective growth of RuO2 nanorods were sputtering power at 50 W and substrate temperature at 200�aC. If the substrate temperature was less than 180�aC, the less mobile growth species tend to deposit in the nongrowth region, and the RuO2 film (not rods) grow in the growth region. If the substrate temperature is higher than 230�aC, a clearly defined pattern can be achieved, but the nanorods lose their one-dimensional feature and become stout rods. When the sputtering power is raised to 60 W, the selective growth temperature region for nanorods decreases. In this work we have outlined the growth domain for area-selective growth of RuO2 nanorods and discuss the morphological variation of RuO2 crystals.