GaAs光导开关的耐压研究

发布时间：2018-05-01 21:57

本文选题：Ga + As光导开关　；参考：《中国科学院大学(中国科学院物理研究所)》2017年硕士论文

【摘要】：半导体光导开关(Photoconductive Semiconductor Switch,PCSS,简称光导开关)作为光电子器件的一种,因其具有外型小,重量轻,工作精度高,高速高频,特别是高增益的非线性工作模式的特点,使其在武器点火、雷达通信、环境监测等领域都有着重要应用,PCSS因此受到了广泛关注。根据应用的特点,光导开关的性能可从两个方面来深入挖掘,一个是在小功率方面的应用,开关的灵敏度和开关比还需进一步的提升;另外一个是在大功率场合的应用,开关的耐压能力限制着开关的功率容量。而且,在实际应用中光电子器件的耐压通常要比理论值小很多,因此提高器件的耐压是PCSS研究中至关重要的一项工作,本文分别从理论和实验上对大功率环境中光导开关的耐压做了研究。在理论上,首先对光导开关的线性工作模式和非线性工作模式的工作原理和特点进行了介绍,并指出GaAs材料的禁带宽度较大,电子迁移率、暗态电阻率和击穿电场都很大,而载流子寿命较小,是良好的制作PCSS材料;其次介绍了开关的芯片主要结构,以及各主要结构层的作用,并从三方面对开关的热效应进行研究,一是入射光脉冲引起的开关温度升高,二是开关处于暗态时暗电流的欧姆效应引起的欧姆生热,三是开关处于导通状态时通态电流引起的欧姆生热。最后,从热击穿和高压击穿两方面分析开关的击穿现象。在实验上,针对入射光斑位置与开关输出功率的关系进行了研究,得到当光斑位置垂直于电极入射时光能利用率较大,故开关输出功率也较大。当光斑平行于电极入射时光能的利用率较小,故开关的输出功率较小。同时,因为光斑位置垂直于电极入射时分布较均匀,所以比光斑平行于电极入射时开关的耐压能力要强。并且,对电极形状、电极间距、欧姆接触、钝化层以及散热等影响光导开关耐压的因素进行了研究。得出了,在相同的条件下具有共面圆角型电极的光导开关具有更小的暗电流,耐压能力更好的结论;对于间距,电极间距越大光导开关的体电阻越大,耐压性能更好,但是过大的体电阻会影响开关的灵敏度,在灵敏度符合要求的情况下电极间距为8mm的器件可以耐5.5kV的高压;针对钝化层,氮化硅的厚度越厚,器件耐压性能更好,覆盖770nm的氮化硅作为钝化层的器件可以耐6kV的高压;最后,外加散热装置可以提高器件的热量耗散能力,使开关的暗电流降低了82%,开关的耐压能力提高了20%。
[Abstract]:As one of the optoelectronic devices, Photoconductive Semiconductor Switch (PCSS) is one of the optoelectronic devices. It has the characteristics of small external type, light weight, high working precision, high speed and high frequency, especially high gain nonlinear working mode, which makes it important in the fields of weapon ignition, radar communication, environmental monitoring and so on. Application, PCSS has attracted wide attention. According to the characteristics of the application, the performance of the optical switch can be excavated in two aspects. One is the application of the small power, the sensitivity of the switch and the switch ratio need to be further improved; the other is the application of the high power, the voltage resistance of the switch limits the power capacity of the switch. Moreover, in practical applications, the pressure resistance of optoelectronic devices is usually much smaller than that of theoretical values. Therefore, improving the voltage resistance of the devices is a very important work in the PCSS research. This paper studies the pressure resistance of the optical switch in high power environment from theory and experiment. The principle and characteristics of the nonlinear working mode are introduced. It is pointed out that the width of the GaAs material is larger, the electron mobility, the dark state resistivity and the breakdown electric field are very large, and the carrier life is small, and it is a good PCSS material. Secondly, the main structure of the core of the switch and the function of the main structure layers are introduced, and the function of the main structure layer is also introduced. The three aspect is to study the thermal effect of the switch, one is the increase of the switching temperature caused by the incident light pulse, the two is Ohm heat caused by the ohm effect of the dark current in the dark state, and the three is the ohm heat caused by the pass state current when the switch is in the conduction state. Finally, the breakdown of the switch is analyzed from the two aspects of the thermal breakdown and the high pressure breakdown. In the experiment, the relationship between the position of the incident spot and the output power of the switch is studied. It is found that the output power of the switch is larger when the spot position is perpendicular to the electrode incident time, so the output power of the switch is small when the spot parallel to the electrode incident time, so the spot position is small. The distribution of the perpendicular to the electrode is more uniform, so the pressure resistance of the switch is stronger than the light spot. And the factors affecting the pressure resistance of the optical switch are studied on the shape of the electrode, the distance of the electrode, the contact of ohm, the passivation layer and the heat dissipation. With smaller dark current and better pressure resistance, the bigger the body resistance of the optical switch is and the better pressure resistance for the spacing, the larger the body resistance will affect the sensitivity of the switch. In the case of the sensitivity, the device with the electrode spacing of 8mm can withstand the high pressure of the 5.5kV; for passivation layer, nitriding The thickness of silicon is thicker, the device has better pressure resistance, the silicon nitride covering 770nm can withstand the high pressure of 6kV. Finally, the external heat dissipation device can improve the heat dissipation capacity of the device, reduce the dark current of the switch by 82%, and increase the voltage resistance of the switch to 20%.

【学位授予单位】：中国科学院大学(中国科学院物理研究所)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN303;O614.371

【参考文献】