| Infrared detectors are the core of infrared technology and have been applied to many fields of national economy, so they have become the front edge and the hot spot of international science research. With the development of modern technology, people has known the advantages of the sensors which urged people to study the infrared detector technology, and then many different sensors come into being. Therefore, we should put more attention on studying them and utilize them continuously. In this article we design the infrared detector to help us analyze the theory and finite elements analysis based on the theory that infrared gas absorbed the infrared radiation and put average pressure on the film. Aiming at figuring out the questions of infrared detectors, a novel room temperature MEMs infrared detectors will be studied in this dissertation and the research work based on the detection theory of gas direct absorption.Firstly, described the function of novel infrared detector in detail. In this article, we give an analysis of the mechanism of the gas as absorption medium for infrared radiation detection in detail. When infrared radiation shine in the device, the gas in the sealed micro-cavity absorbs the incidence infrared energy through the transition between the vibration energy levels and the rotation energy levels of the molecules, then the gas molecule become un-excited through the gas molecules' collision in which processed the absorbed energy will be transformed to the average heat energy of the gas. The increased heat energy will result in the increasing of the gas pressure in the cavity and the deformation of the elastic film, which is the movable plate of the microcapacity change of the voltage potential of the elastic film. Finally GaN/Al GaN HEMT can detect the voltage and out the current to detect infrared radiation.Secondly, the software of ANSYS can be used to simulate the GaN/AlGaN elastic film. We divide this work into two parts: First for the mechanical properties, we established a film solid model, then we keened on the stress analysis and the internal stress distribution influenced by the mechanical deformation. And as a conclusion, the deformation of the film with an uniform pressure decreased linearly with the increase of mechanical stress. The internal stress reaches maximum at the center of the film, and we should put the GaN HEMT on the point with maximum internal pressure. Therefore the thinner the film is, and the larger the film area is, the more sensitive measurement of the force, and get the greater deformation of the film. Then the piezoelectric effects are simulated and we can get the value of the voltage potential distribution which help us to optimize the parameter that influence the film.Thirdly, Sentaurus TCAD is used to analyze the key structure of infrared sensorGaN HEMT. We designed the structure of the HEMT, and simulate the output current curves to analyze the electrical characteristics, and give an optimization of the structure parameters that affects the electric ability, such as AlGaN barrier doping concentration, traps concentration, the amount of the polarization charge, and the schottcky barrier height of AlGaN, and the Al composition of AlGaN.Finally, we conclude that the gas expand after the energy increased by infrared radiation absorption, and thus the pressure changes on the film stress is applied. According to the piezoelectric polarization of AlGaN/GaN heterojunction, the current can be got by the HEMT. All in all, we fitting the relationship curve between the current and the temperature detected with the linearity of 0.037,whitch can reflect the sensitive to infrared radiation. |
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