Investigation Of Preparation And Performance Of Infrared Detector Based On PZT Ceramics

Lead zirconate titanate(PZT) is a sort of ferroelectric material, which has good pyroelectric properties. Since the pyroelectric infrared detectors of domestic production have low performance and production efficiency, the related researches are requisite and valuable. This thesis mainly does research on the patterned carbon infrared absorber, preparation of PZT ceramics as sensitive elements and thermal-insulated structure to advance performance and production efficiency of detectors. The single channel detector of double elements and double channels detector of four elements have been designed, fabricated and measured on the test system of pyroelectric infrared detector, including the voltage responsivity(RV), noise equivalent power(NEP), specific detectivity(D*) and thermal response time(τT).1 The patterned ultraviolet curing ink was achieved by lithography to satisfy requirement of industrial production. If the ratio of ink components was 3:1:0.5 and the mixed ink was coated on the surface of substrate at a speed of 2800 rpm for 30 s, meanwhile, the ink coating was exposed in UV(365nm) for 2min by contacting lithography, the ink absorber was of high performance, which remained clear edge definition, intact figure and a spot of cavities on the surface of ink. The experimental result demonstrated ultraviolet curing ink had high absorbance within the range of 86%~90% and 82%~89% at 3μm~5μm and 8μm~14μm, respectively.2 The single channel detector of double elements and double channels detector of four elements were designed, including circuit design, sensitive element design, thermal-insulated structure and packaging design. The above two detectors were fabricated by lithography of UV curing ink, laser etching process, ultrasonic wire bonding and automatic dispenser techniques.3 The single channel detector of double elements and double channels detector of four elements were measured on the test system of pyroelectric infrared detector. When the chopping frequency was 5.3Hz, the voltage responsivity, noise equivalent power, thermal response time and specific detectivity of the former detector were 1.186×103V/W, 5.1×10-10 W, 40 ms and 3.67×108cmHz1/2W-1, respectively. For later detector, D*of both channels were different slightly. However, the difference between two channels decreased with the increase of frequency. When the frequency turned 138.3Hz, D* of both channels could reach 3.4×109cmHz1/2W-1, which indicated detector had good performance at high frequency.4 In constract with detector with PI thermal-insulated layer, detector with back-dangling insulation structure had better performance, whose voltage responsivity and specific detectivity were 1.55×103V/W and 5.24×108cmHz1/2W-1, respectively. The value of RV and D* increased by 43.5% and 42.8%, respectively. The maximum value of D* was 5.59×109cmHz1/2W-1. Furthermore, the heat-insulated groove of sensitive element could decrease noise equivalent power and advance detectivity significantly. D* of detector with six heat-insulated grooves could reach 6.87×109cmHz1/2W-1. This result demonstrated the influence of heat-insulated grooves on detectivity was greater than that of thermal-insulated structure.