resistances comes with higher Johnson–Nyquist noise. Detecting materials The two most commonly used IR radiation detecting materials in microbolometers are amorphous silicon and vanadium oxide. A problem with some potential materials is that to create the desirable properties their deposition temperatures may be too high for CMOS fabrication processes. Much research has been done to test the feasibility of other materials to be used. Those investigated include: Ti, YBaCuO, GeSiO, poly SiGe, BiLaSrMnO and protein-based cytochrome C and bovine serum albumin. Amorphous Si (a-Si) thin films can easily be integrated into the CMOS fabrication process using low deposition temperatures, is highly stable, has a fast time constant, and has a long mean time before failure. To create the layered structure and patterning using the CMOS fabrication process requires temperatures to stay below 200˚C on average. a-Si also possesses excellent values for TCR, 1/f noise and resistance when deposition parameters are optimized. Vanadium oxide thin films may also be integrated into the CMOS fabrication process although not as easily as a-Si for temperature reasons. VO is an older technology than a-Si, and its performance and longevity are inferior. Deposition at high temperatures and performing post-annealing allows for the production of films with superior properties. VO2 has low resistance but undergoes a metal-insulator phase change near 67 °C and also has a lower value of TCR. On the other hand, V2O5 exhibits high resistance and also high TCR. Many phases of VOx exist although it seems that x≈1.8 has become the most popular for microbolometer applications. A thermal imaging camera with a Vanadium Oxide Micro-bolometer detector is more stable, compact, and sensitive compared with any other technology though VOx is older technology. The market share of VOx is much higher than any other technology. VOx market share is 70% where as Amorphous Silicon is 13%. Also, VOx technology based thermal cameras are being used in Defence Sector due to its sensitivity, image stability and reliability. The use of infrared optical antennae together with small-size microbolometer materials can enhance its detection efficiency. Active vs passive microbolometers Most microbolometers contain a temperature sensitive resistor which makes them a passive electronic device. In 1994 one company, Electro-Optic Sensor Design (EOSD), began looking into producing microbolometers that used a thin film transistor (TFT), which is a special kind of field effect transistor. The main change in these devices would be the addition of a gate electrode.