以溶膠凝膠法製備非冷卻型紅外光感測薄膜V1-x-yWxSiyO2及其優質係數之研究

Abstract

TheV1-x-yWxSiyO2 composite thin films are thermochromic materials for the uncooled microbolometer due to their high temperature coefficient of resistance (TCR) at room temperature. In this study, V1-x-yWxSiyO2 thin films were prepared by sol-gel method followed by spin coating process, and then calcined at 500℃~600℃ under a reducing gas flow in an atmospheric control furnace. The bolometers are patterned by photolithography process followed by wet etching. The electrical properties of the thin films were measured by a 4-point probe meter. The surface morphology was obtained by AFM. In addition, the ohmic contact V1-x-yWxSiyO2 composite thin films were fabricated as bolometers by sputtering process; the bolometer is connected with a DC source and loaded a resistance equal to the resistance of bolometer, and the bolometer is exposed to a filtered radiation of a 500K black body to measure its responsivity and noise. The open circuit voltage is measured using a lock-in amplifier modulated by a chopper and the incident radiation. The V1-x-yWxSiyO2 composite thin films characterized a switching temperature ranging from 20℃ to 70℃, accompanied with a temperature coefficient of resistance (TCR) 11%/K at room temperature. The composite films doped with tungsten at mixing ratio (Wx+/V4+) of 0.02 show a sharp hysteresis loop, whereas the composite films doped with silicon at mixing ratio (Siy+/V4+) of 0.15 has a tight bandwidth of hysteresis loop. A variety of thermal-optical characteristics can be achieved with various dopant concentrations and process conditions. Figures of merit for composite thin films were further evaluated on the one-element bolometers without air-gap suspending structure. Results show that the detectors exhibit a responsivity over 2600 V/W and detectivity 9*106 cm Hz1/2 /W at 60Hz chopper frequency measured at room temperature.