This paper presents the formation and the characterization of silicon germanium oxide (SixGeyO1-x-y) infrared sensitive material for uncooled microbolometers. RF magnetron sputtering was used to simultaneously deposit Si and Ge thin films in an Ar/O2 environment at room temperature. The effects of varying Si and O composition on the thin film’s electrical properties which include temperature coefficient of resistance (TCR) and resistivity were investigated. The highest achieved TCR and the corresponding resistivity at room temperature were -5.41 %/K and 3.16×103 ohm cm using Si0.039Ge0.875O0.086 for films deposited at room temperature.

This paper describes the design and modeling of a smart uncooled infrared detector with wavelength selectivity in the long-wavelength infrared (LWIR) band. The objective is to enhance the probability of detecting and identifying objects in a scene. This design takes advantage of the smart properties of vanadium dioxide (VO2): it can switch reversibly from an IR-transparent to an IR-opaque thin film when properly triggered. This optical behavior is exploited here as a smart mirror that can modify the depth of the resonant cavity between the suspended thermistor material and a patterned mirror on the substrate, thereby altering wavelength sensitivity. The thermistor material used in the simulation is vanadium oxide (VO2). The simulation results show that, when VO2 is used in the metallic phase, it reflects IR radiation back to the suspended VOX and enhances IR absorption in the 9.4-10.8-mu m band. When the film is switched to the semiconductor phase, it admits most IR radiation, which is then reflected back to the suspended VOX by a patterned gold thin film under an SiO2 spacer layer. The spacer layer is used to increase the resonant cavity depth underneath the microbolometer pixel. Thus, the peak absorption value is shifted to 8-9.4 mu m, creating the second spectral band. The detector is designed with a relatively low thermal conductance of 1.71 x 10(-7) W/K to maximize responsivity (R-v) to values as high as 1.27 x 10(5) W/K and detectivity (D*) to as high as 1.62 x 10(9) cm Hz(1/2)/W, both at 60 Hz. The corresponding thermal time constant is equal to 2.45 ms. Hence, these detectors could be used for 60-Hz frame rate applications. The extrapolated noise equivalent temperature difference is 14 and 16 mK for the 8-9.4- and 9.4-10.8-mu m bands, respectively. The calculated absorption coefficients in the two spectral bands were 59% and 65%, respectively.