【作者】 郑鑫；

【导师】 程湘爱；

【作者基本信息】 国防科学技术大学 ， 光学工程， 2011， 硕士

【摘要】 随着光电探测器在军事和民用等诸多领域的广泛应用,半导体材料与半导体光电探测器的激光辐照效应越来越受到人们的重视。虽然光电探测器种类繁多,其光谱探测范围可从紫外到远红外,但是每一种光电探测器都存在特定的光谱探测范围。尽管光电探测器在波段内连续激光辐照下的效应研究已经较为成熟,但是在实际的光电对抗中,对探测器进行干扰和毁伤的激光波长不一定恰好位于探测器的响应波段之内,开展光电探测器在波段外激光辐照下的效应研究具有重要现实意义。有关波段外激光对光电探测器的作用机理的研究工作,国内外文献中还鲜有报道。本文选取目前已经广泛应用的锑化铟(InSb)光电探测器作为研究对象,开展其在波段外连续激光辐照下的效应研究,探索波段外激光对光电探测器的作用机制。对光导型(PC)锑化铟探测器进行了波段外连续激光辐照实验,得到了与以往报道不同的实验现象:探测器吸收较多的波段外激光能量后,呈现出与波段内激光辐照下类似的响应输出。研究结果表明:当波段外激光辐照光导型探测器时,探测器吸收激光能量后温度升高。在探测器的温升过程中,存在一个转变温度T0,当探测器的温度T<T0时,载流子浓度基本不变,迁移率随温度的升高呈T-2.35趋势下降,引起探测器的电导率减小,电阻增大,响应输出电压升高;当T>T0时,热激发载流子浓度随温度的升高呈指数增长,电阻急剧减小,超过了载流子迁移率降低对电阻的影响,响应输出电压下降。光电导探测器在较高功率密度波段外激光辐照下的响应特性是载流子的浓度和迁移率在温度影响下共同作用的结果。通过对实验现象的分析总结,提出了光导型探测器在强光辐照下的行为可以采用一个光敏电阻和热敏电阻等效代替的模型。这对进一步完善半导体内载流子输运模型提供了依据。对光伏型(PV)锑化铟探测器进行了波段外连续激光辐照实验,发现当初始载流子浓度很低时,光伏型光电探测器对波段外激光的电压响应方向与波段内激光辐照下的响应方向相同。对光伏型探测器在波段外激光辐照下的电压响应机制进行了分析,认为当初始载流子浓度很低时,热生电动势是光伏型探测器在波段外激光辐照下电压响应的主要机制。采用波段内激光提供不同的初始载流子浓度,研究了双波段激光辐照下,光伏型锑化铟探测器在波段外激光辐照下的输出响应规律,发现较高的初始光生载流子浓度能够促进探测器对波段外激光能量的吸收,探测器温度升高后,PN结内建电场减弱,分离电子-空穴能力下降,探测器响应率降低。通过以上工作,本文较系统地介绍了锑化铟探测器在较强波段外连续激光辐照下的响应输出规律,并分析了其作用机理,认为较强波段外激光能够对光电探测器产生有效的干扰,双波段组合激光辐照能够促进光电探测器对波段外激光的吸收,提高波段外激光的干扰效果。更多还原

【Abstract】 With the widespread use of photoelectric detectors in different aspects, especially for military and civil purpose, more and more attentions are being paid to the irradiation effects of semiconductor materials and photoelectric detectors. The spectrum of the photoelectric detectors ranges from ultraviolet to far-infrared since there are many kinds of semiconductor materials. However, for a specific detector, it could only response to a specific spectrum range. In other words, every kind of detector has a cut-off frequency, which is mainly determined by the band gap energy. Generally speaking, we call the laser above-band laser, whose photon energy is larger than the band gap energy; otherwise call it sub-band laser. It is well known for the irradiation effects of detectors by above-band lasers. However, the lasers which are adopted to disturb photoelectric detectors are probably sub-band lasers in many cases. Therefore, it is of great practical importance to carry out the research on the irradiation effects of photoelectric detectors under sub-band laser.This dissertation is focused on the irradiation effects of InSb detector, which has been widely used. Exploratory research is made on the mechanism of several effects with InSb detector.A new phenomenon is observed when a photoconductive InSb detector with 0.228eV band gap is irradiated by 10.6μm laser, whose photon energy is 0.12eV. The detector is heated by this sub-band laser, due to absorption of photons. A critical temperature T0 exists in this process. When the temperature of the detector, T, is lower than T0, the number of carriers changes little while the conductivity changes because of the change of electron mobility. The mobility decreases with the increase of temperature and varies as T-2.35. At T>T0, the concentration of thermally-activated carrier increases with temperature proportional to exp (-Eg/2k0T). As a result, the influence of carrier concentration becomes more and more important. As a result, the output of the detector decreases. In a word, the output voltage of photoconductive detector rests with the temperature dependence of mobility and concentration of carriers. This work provides an experimental basis for consummating the carrier transport model.We carry out experiments on photovoltaic detectors irradiated by sub-band lasers, and get the rules of dynamic responses. It is found that the voltage response of photovoltaic detector to sub-band laser is similar to that to above-band laser. The voltage response mechanism of photovoltaic detector under the irradiation of sub-band laser is analyzed. Comparing with the photovoltage and temperature difference-EMF (electric motive force), thermovoltage is the main mechanics of voltage response under sub-band laser irradiating. Exploratory research is carried out to investigate the influence of the concentration of initial free carriers to the output of photovoltaic detector under sub-band laser irradiation. A lower concentration of initial free carriers leads to a notable thermovoltage; otherwise, the build-in electric field will weaken and the response ability will decrease, due to the temperature rise induced by free carrier absorption.This dissertation is focused on the mechanism of the interaction between higher power sub-band laser and InSb detector, and find that out-band laser could disturb photoelectric detectors effectively. Besides, the simultaneity irradiation of sub-band and above-band laser could improve the absorption of sub-band laser, which could improve the disturb impact of sub-band laser.更多还原