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用波长1064nm,触发光能为0.5mJ的激光脉冲触发电极间隙为4mm的半绝缘(SI)GaAs光电导开关,当偏置电压达到4kV时,开关并未引发自持放电,而是进入非线性(lock-on)工作模式,即开关处于光控预击穿状态。分析认为:通过激子的产生和离解激子效应贡献了光电导;碰撞电离、雪崩倍增、激子效应补充了因外界光源撤出后所需的载流子浓度和能量。在上述因素的相互作用下,SI-GaAs 光电导开关并没有引发自持放电而是处于光控预击穿状态,丝状电流特性影响着开关的损伤程度。 相似文献
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A 4 mm gap semi-insulating(SI) GaAs photoconductive switch(PCSS) was triggered by a pulse laser with a wavelength of 1064 nm and a pulse energy of 0.5 mJ.In the experiment,when the bias field was 4 kV, the switch did not induce self-maintained discharge but worked in nonlinear(lock-on) mode.The phenomenon is analyzed as follows:an exciton effect contributes to photoconduction in the generation and dissociation of excitons. Collision ionization,avalanche multiplication and the exciton effect can supply carrier concentration and energy when an outside light source was removed.Under the combined influence of these factors,the SI-GaAs PCSS develops into self-maintained discharge rather than just in the light-controlled prebreakdown status.The characteristics of the filament affect the degree of damage to the switch. 相似文献
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With its unique features, photoconductive semiconductor switch (PCSS) is generally recognized today as a promising power electronic device. However, a major limitation of PCSS is its surprisingly low voltage threshold of surface flashover (SF). In this paper, an experimental study of surface flashover of a back-triggered PCSS is presented. The PCSSs with electrode gap of 18 mm are fabricated from liquid encapsulated czochralski (LEC) semi-insulating gallium arsenide (SI-GaAs), and they are either un-coated, or partly coated, or en- tirely coated PCSSs with high-strength transparent insulation. The SF fields of the PCSSs are measured and discussed. According to the experimental results, the high-dielectric-strength coating is efficient in both reducing the gas desorption from semiconductor and increasing the SF field: a well-designed PCSS can resist a voltage up to 20 kV under the repetition frequency of 30 Hz. The physical mechanism of the PCSS SF is analyzed, and the conclusion is made that having a channel structure, the SF is the breakdown of the contaminated dielectric layer at the semiconductor-ambient dielectric interface. The non-uniform distribution of the surface field and the gas desorption due to thermal effects of semiconductor surface currents are key factors causing the SF field reduction. 相似文献
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