RF sputtered silicon-germanium and silicon germanium oxide thin films for uncooled infrared detectors

The objective of this work is to test the feasibility of using radio frequency (RF) magnetron sputtered SixGe1-x and Si xGe1-xOy thin films as the sensing material in uncooled infrared detectors, and find a suitable combination of Si xGe1-x and SixGe1-xOy thin films for this purpose. Thus, fabricating and characterizing microbolometers by using SixGe1-x and SixGe1-xO y thin films as the sensing material are the ultimate goal of this work.; Thin films of SixGe1-x and SixGe 1-xOy were deposited by RF magnetron sputtering at room temperature from a single target of SixGe1-x in Ar or Ar : O 2 environment. The silicon and oxygen concentrations were varied in a parametric investigation of the dependence of the electrical and optical characteristics of the thin films on composition. As Si concentration was increased in SixGe1-x films, the temperature coefficient of resistance (TCR) was decreased. For SixGe1-xO y films, the addition of oxygen to SixGe1-x, increased the activation energy, and TCR. TCR was measured to vary from -2.27 %/K to -8.69 %/K. The optical bandgap was increased with the increasing concentration of oxygen in SixGe1-xOy. To compare 1/ f-noise from each film, the value of the volume normalized Hooge coefficient was determined for all the films. The normalized Hooge coefficient was found to increase with the increasing concentration of O2. With the addition of O2 to SixGe1-x, the transmittance of the films found to be increased while the reflectance remained almost constant. The optical bandgap was increased with the increasing concentration of O2. A suitable atomic composition of SixGe1-x Oy for uncooled infrared detector applications was found to have a TCR of -5.10 %/K.; Microbolometers of doped SixGe1-x were fabricated and characterized. A TCR of 1.25%/K with a device resistance of 41.4 KO was achieved. Thermal conductivity was found to be 1 x 10-5 WK-1 for these doped SixGe1-x microbolometers. The presence of high 1/f-noise was observed which caused to degrade bolometers performance.; Uncooled SixGe1-xOy microbolometers were fabricated and passivated by forming gas at 250°C for different interval of time to reduce noise. The value of normalized Hooge coefficient for 1/ f-noise (Kf) was decreased from 7.54 x 10-7 to 2.21 x 10-10 after 8 hours of forming gas passivation performed at 250°C. The highest responsivity and detectivity obtained from SixGe1-xOy:H microbolometers were 1.05 x 104 (V/W) and 8.27 x 106 (cm-Hz1/2/W) respectively while the room temperature TCR was -4.80%/K. The lowest thermal conductivity was found to be 4 x 10-8 WK-1.; Cavity based tunable Fabry-Perot microspectrometer was fabricated using bulk micromachining technology. The device was fabricated by using Al 2O3 as the support layers for both top and bottom part of the cavity. Al was used as the mirror and electrode materials for both top and bottom parts. Polyimide was used as the sacrificial material to form the cavity. The device is still under test to measure its performance.