Unit Simulation And Properities Measurement Of Terahertz Microbolometer

Terahertz waves, which are in the transition zone from electronics to photonics, has aroused increasing interest of the scientific community for their unique nature. THz imaging detection is an important part of terahertz technology application. THz microbolometer that has the advantages of lower cost, portability, reliability and bandwidth composes significant part of THz imaging detectionIn this paper, the author makes microbolometer have a better performance on THz detection by improving its structure. This pushes the application of microbolometer to THz field from infrared field. The unit of THz microbolometer is 75μm×75μm, employing L-sharp bridge leg. One metal film is added at the top of the detector as the THz absorption layer and one electric connecting layer is added at the bottom of the detector in order to connect the Peripheral circuit.Terahertz absorption layer is one metal thin-film and effect of medium is ignored. According to electromagnetic theory, the absorption rate can reach 50%. In the experiment, the absorption rate of the THz absorption layer can be more than 20% by improving the method. The metal film can be blackened by Fluoride ion’s bombardment on the surface to improve the absorption rate. Therefore, THz absorption layer performances better. To some extent, this new method can solve the problem that the thickness of the metal film can not achieve the requirement of the theory for the restriction of technological conditions.The simulation analysis of THz microbolometer was carried out. Broadening the bridge leg can increase the mechanical stability of the detector and reduce the thermal response time, meanwhile, it will reduce the temperature rise. Based on the result of experiment, 2.2μm is proper width for the bridge leg. As for increasing the thickness of bridge deck protective layer, it can increase the mechanical stability better than broadening the bridge leg, but it will bring other results, for example, it reduces the temperature rise and increases the thermal response time. Thus, 450 nm is proper thickness of the bridge deck protective layer.A refractive optical lens has been designed to meet the need of THz detection. The simulation analysis is carried out by using Tracepro software and the structural parameters of the optical lens. The filed angle is 16.3° and the resolution is 20 lp/mm. As a result, the lens can achieve the requirement of imaging of THz microbolometer.The preparation and test of THz microbolometer are completed. The response rate of the unit reduces with the increase of chopper’s frequency. Under different frequencies, NEP are all better than 300 p W/Hz1/2, as the average thermal response time is 10.93 ms.