Effect of Titanium Doping on the Characteristics of Temperature Coefficient of Resistance of Multi-phase Vanadium Oxide Thin Films

• Main Authors: Shan-Wei Fan, 范珊瑋
• Other Authors: Tai-Bor Wu
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/98521409696142355871

碩士 === 國立清華大學 === 材料科學工程學系 === 94 === Vanadium oxides compound (V2O3, V2O5, and VO2, etc.) is a well known thermal-sensitive material, undergoing a phase transition from a low temperature, semiconducting state to a high temperature, metallic state. This change is accompanied by an abrupt resistivity modification near room temperature, made vanadium oxide a candidate material for bolometric sensors application. In this application, the bolometer sensitivity is directly related to the temperature coefficient of resistance (TCR), defined as the slope of log resistivity. To produce a highly sensitive uncooled microbolometer, the development of a thermometric material with a high temperature coefficient of resistance is essential. In this worker, Vanadium oxide thin film was fabricated by metal organic chemical vapor deposition (MOCVD) from pure vanadium tri-isopropoxide oxide precursor. Furthermore, we used Titanium as a dopant during the MOCVD process. Using MOCVD method, offers advantages of both high deposition rate, low fabricated temperature, and particular the ability easily to tailor the chemical composition, The correlations between the crystal structures and the growth recipes were investigated by the x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and x-ray photoelectron spectroscopy (XPS). Also, the electrical characteristics of vanadium oxide thin films resulted from the crystal structures and phase changes were measured by four-point probe equipment. Compared with pure vanadium oxide thin films, titanium-doped vanadium oxide thin films obviously showed a higher temperature coefficient of resistance, lower resistivty and negligible electrical hysteresis. It can be concluded that the developed vanadium-titanium oxide is an excellent electrochromic material for the fabrication of high performance uncooled mircobolometer.