Simulation And Design Of Uncooled Microolometer For Terahertz Range

The terahertz (THz) region of the electromagnetic spectrum lies in the gap betweenmicrowaves and infrared, terahertz frequencies are commonly refers to electromagneticradiation in the0.1~10THz area. This so-called ‘terahertz gap’ has been defined by therelative lack of sources, detectors for terahertz waves. Terahertz imaging has attractedmuch attention in recent years, because the technique can be applied to manyapplication fields such as nondestructive analysis, security detecting, and biomedicine.Studying THz detection imaging technology of real-time detection, entire columnimaging, working at room temperature, small size and low cost is of great significancefor promoting terahertz technology development and practical application. Themicro-bridge technology based on the microbolometer is an important technical meansto realize THz detectors.To make the uncooled microbolometer work within the range of THz, theimprovement of first importance is to add the absorption film by the addition with thethickness optimized to raise the index of absorption, secondly to extend or narrow thearm that provides the thermal conduction of the bolometer as an improvement of theheat separation structure, and expand the absorption area of the cell is to increase theabsorption amount of THz radiation. In this paper thermal simulation and mechanicalsimulaiton of the structure of the microbolometer have been carried out by theIntelliSuite software, the simulation result suggest that widening the arms damage thethermal performance of the cell largely, but bring the improvement of the mechanicalproperty very weakly, and expanding the cell area can significantly improve the thermalperformance, but it also significantly reduces the mechanical property.Meanwhile, each cell designed in this paper have been actually manufactured, andthe observation results show that the size of the cell area significantly affect itsmechanical property, and widening the arms can not significantly improving celldeformation, which is consistent with the mechanical simulation results.NiCr alloy is a suitable material for the THz absorbing film, theoretical analysisshows that the NiCr film have absorption peak for a certain frequency of THz radiation, and the absorption peak centered between a thickness of about10nm~30nm. Thereforethe index of THz absorption can raised up by optimizing the thickness of NiCr film. Theactual test data shows that within the range below1THz, the index of THz absorption ofNiCr film is very weak; and within the range of1THz to2.5THz, the index presents aupward trend, which is approximately10%to20%within the thickness between10nmto30nm. The test result is roughly in accordance with the theoretical analysis.