Design Of Pyroelectric Sensor Based On Carbon Nanotubes Absorbed Layer

In recent years, Infrared sensor is developed very fast in the military and civil market,especially in the aerospace and digital products. Pyroelectric infrared sensor is one of the hottopics in the study of uncooled infrared detector. It has a high potential application in the veryfast developed wearable devices. The development direction of Infrared sensors is array,miniaturization and low cost at present. In this paper, the main research works are thefollowing several aspects:1. First of all, the structure of the detector is analyzed and the process flow of preparationof detector is designed. The most important is to optimize the pyroelectric crystal thinning andpolishing. For thinning and polishing process, a level meter is used to test the crystal surfaceroughness which is polished by three different kinds of polishing liquid and polishing mat, andthe special feeder drops is used to make thinning and polishing more evenly. We use a AFM totest the surface of crystal morphology after polishing. A pyroelectric coefficient test systemwas built to compare the pyroelectric coefficient of crystal with different thickness anddifferent surface roughness. The crystal of upper and lower electrode is made by magnetronsputtering.2. We use carbon nanotubes as the infrared absorption layer of detector instead of thetraditional metal materials. Carbon nanotubes were dispersed by physical and chemicalmethods, and CTMAB as the dispersant of carbon nanotubes is used in the process ofdispersion, and physical process mainly includes the grinding, ultrasonic oscillation andcentrifugal. Then, use screen printing to make carbon nanotubes which joined the filmformers evenly daub on pyroelectric crystal surfaces to form the infrared absorption layer.Finally, the relative spectral response of single-walled carbon nanotubes and multi-walledcarbon nanotubes was tested by a relative spectral response testing system.3. The performance of the infrared detector that combined with the probe amplificationcircuit was tested. We also designed a test system to test the voltage response of detector whichcrystal thickness is200μm、100μm and50μm. At the same time, three different absorptionlayer of detector performance is tested. At last, Pyroelectric detector encapsulation structure is briefly expounded.