Investigation of doped and undoped VOx films for terahertz microbolometer applications

Abstract

The microbolometer technology has proved its potential in the Infrared (IR) region due to its low fabrication costs, and room temperature operation, making this technology desirable to be used in various applications, and this interest has recently expanded into the Terahertz (THz) region as well. The detection in microbolometers is achieved through the absorption of THz radiation which subsequently heats up and is sensed by the temperature sensitive material at the core of the device. This temperature sensitive material is typically based on VO_x, which exhibits a sufficient change in resistance with temperature. While this temperature sensitive material is useful in the IR, the low energy of the THz wave compared to the background radiation makes it a challenge to operate the device at room temperature and show a large change in resistance with respect to the slight change in temperature. Metal doped VO_x films can show a better performance however these effects are not well understood in the THz region. In this study, Tungsten (W) doped and undoped VO_x films are fabricated and then analyzed using Time Domain THz Spectroscopy. The DC electrical properties of the films as well as their optical behaviors in the region of 0.2-2.0 THz are analyzed as a function of temperature. The metal doping is seen to affect the overall electrical and optical response of the film. Understanding this dependence is key to achieving a better film for applications in the THz region.