The Pyroelectric Devices Based On Mn Doped PZT And P(VDF-TrFE) Composite Films

The composite film based on ceramic/polymer is a hot research topic about pyroelectric material. The pyroelectric coefficient of the composite film is very large; the composite film has excellent dielectric properties; and the flexibility and mechanical properties of the composite film is great, so the composite film can be bent and folded arbitrary. The preparation process of the composite file is simple, and it has low cost, and low preparation temperature. The composite film can be compatible with the integrated readout circuit(ROIC). No matter unit pyroelectric devices or multiple pyroelectric devices, they both have very good application prospects. The PZT/P(VDF-TrFE) composite film have received comprehensive research attention, but the multiple device developed very slow due to the limitation of the composite material properties. This article change the mass ratio of the Mn dropped PZT and P(VDF-TrFE) to prepare composite films, and research effect of the mass ratio on composite films pyroelctric coefficients, dielectric constant, dielectric loss, volume specific heat and other parameters. In order to research the effect of mass ratio on devices performance, the article computes the detection optimal value FD, and measure the IR absorptivity. And this article discussed how the infrared absorption can affect the performance of the devices. Based on unit device, the composite films based multiple devices and readout circuit were designed and fabricated.1 This article using Mn dropped PZT as the ceramic phase, and using P(VDF-TrFE) as basal, to prepared the big slice composite films by flow casting. Use Ni/Cr alloy as target to prepare and electrode, clip the film by metal plat to polarize the film.2 This article fabricate four kinds composite film and sensor with different mass ratio of Mn dropped PZT and P(VDF-TrFE). With the increase of the ceramic phase, the pores in the composite films were increased too. In order to research the effect of mass ratio on material properties, article measured pyroelctric coefficients, dielectric constant, dielectric loss and volume specific heat. And use these parameters to compute the detection optimal value FD, measured the IR absorptivity of these composite files to research the effect of mass ratio on devices performance. By compared the experimental data, we get the best mass ratio, and the best mass ratio of PZTM to P(VDF-Tr FE) is 0.7:1. Then we use the sensor to fabricate the pyroelectric devices, and measure the electrical properties of these devices. Through contrast the different point about FD and electrical properties of devices, we get the conclusion that the infrared adsorption of the sensor can affect the performance of the device. And we get the best mass ratio of the Mn dropped PZT and P(VDF-TrFE) is 0.7(g):1.0(g).3 Improve the unit detector circuit performance. Delete the resistance Rg with high resistance. After delete the resistance Rg, the Power-on time of device will increase, but when the output signal of device stable, the signal waveform is good. The article series connect a capacitance to filtering the DC component in the signal.4 Based on unit device, the multiple pyroelectric infrared detectors was prepared. Utilize the characteristics of flexible bending of composite film, we make the sensor and PCB board to form electrical connection by paste method. The insulation structure of device is substrate tunneling structure. Because of the brace by the PCB pad and silver size, the thermal insulation structure can be formed.5 This article designed unit select readout circuit by switching characteristics of transistors. The select readout circuit includes switch module and voltage-follower module. The subject of the switch circuit is switching transistors, and the voltage follower module isolate the connection between the switch module and sensor, so that the switching noise of the switching module do not affect the performance of sensor. And the article simulates the unit switch circuit by Multisim, verify the feasibility of the unit switch circuit. And then, the article extend the unit circuit and simulate the two channel switch circuit, and get two channel sinusoidal signal that time sharping readout, when a channel signal readout, the other do not readout. The feasibility of the circuit is verified by the simulation. The article also designed the control circuit; the main module of the control is micro controller. The control circuit can control the ON and OFF of the switch circuit. Connect the multiple devices, control circuit and switch circuit, then measure the electrical properties by the electrical performance test platform, and we get two channel time sharping readout sinusoidal signal.