| The infrared detectors are rapidly developed, among all of those detectors, the uncooled IR micro-bolometer is the most widely used,it has mamy advantages such as power-consumption, ease of integrate and low-cost. At present, most micro-bolometers measure infrared thermal radiation based on only one wavelength response windows of8-14μm.With the maturity of infrared detection technology, the terahertz field is located between in the infrared wave and the millimeter wave get much attention. Its wavelength range is between3mm to30μm, according to frequency, it belongs to the far infrared frequency band.The terahertz sensor has particular use in semiconductor field, superconducting material field, biochemistry field and communication field. And it plays an important role in the development of technology innovation and the national economic security. But because of the low teraertz photon energy, the background noise of radiation sources has a great influence on it. That must be the biggest cause of the feeble light sources of terahertz radiation. Further more, it brings a lot of difficulty to detect the terahertz signal.At present, THz micro-bolometer of commercialization is the most sensitive direct detector, the response presents a higher degree. The work-frequency range is between0.1THz to100THz, the noise equivalent power (NEP) is4.5x10-15W/Hz1/2, the response rate is about8.14×106V/W, and the corresponding attenuation is between10Hz to200Hz.To boost the sensitivity of the device further, a new type of terahertz detector—antenna-coupled microbolometer is proposed. The new type detector can effectively overcome the deadly factors of alreadyly existing terahertz light source, it will be slightly limited by the low output power of terahertz radiationsources and the high thermal radiation background noise of terahertz range, further more, it can effectively use the advantages of antenna to realize special function of tuning and polarization detection etc.This paper has discussed the work mechanism of antenna-coupled microbolometer, analysised seven different antenna of the antenna-coupled microbolometer, and finally established for two structures. One is the dual-patch microstrip antenna-coupled microbolometer, and the other is the log-periodic antenna-coupled microbolometer. These two structures has larger effective absorption area witch is very beneficial for terahertz wave detection. In addition to design the two structures, also has some performance simulation with two professional software—HFSS for antenna and IntelliSuite for MEMS electromagnetic simulation.By analyzing the simulation results, it was found that, the dual-patch micro-strip antenna-coupled microbolometer working in the terahertz range can reach a power gain to10.31dB, the maximum absorption of power to0.881w has been gained, also it has a good impedance matching characteristics; the log-periodic antenna-coupled microbolometer witch working in the terahertz range can reach a power gain to12.32dB, the maximum absorption of power to2.113w has been gained, also a very good directional could be reached. By using IntelliSuite, the two antenna structures were designed, the temperature rising and deformation distributed was gained. The results show that when the device use the bridge-structure, with the long legs, the more narrower width, the more thinner thickness, will cause the smaller thermal-conductivity, the greater temperature rising and witch means the thermal properties of the device is more reliable. The buckling load of the two structures are1682.69MPa and1350.69MPa respectively. Therefore, in the fabrication of the micro-bridge, the tensile stress should be controlled within these values. |
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