| Photoconductive Semiconductor Switches(PCSS's)is a new semiconductor device that combines ultra-short laser pulse with photoelectric semiconductor(GaAs,InP and so on). PCSS's have the excellent base operating characteristic of electrical apparatus,such as the short rise-time of electromagnetic pulse,fast response speed,wide change of dynamic state,the good ability of optoelectronic isolation and anti-interference.Therefore it is widely used in some field,such as ultra-speed electronics,ultra-band radar,ultra-band communication and the technology of transient electromagnetic wave.The intrinsic donor level deep EL2 in semiconductor GaAs is investigated in this paper.Based on the EL2 donor level,the laser pulse which is longer than intrinsic absorption edge can be absorbed.The absorption principle when PCSS's are exposed by laser in 1.13eV and 1.167eV photon energy.In the condition of 1.13eV photon energy,photo-conductance deduces to a minimum before rises to a maximum,finally, arrives at a saturation value.The phenomenon is connected with the conversion from EL20 neutral energy level to metastable energy level EL2* and EL2+ level in semiconductor GaAs. When the PCSS is irrigated by 1064nm laser,there are three modes,linear mode,nonlinear mode and compound mode.The EL2 energy level plays different roles in three modes. Especially in the compound mode,the EL2 energy level can be well used to explain the late effect.The relationship between rise time of output ultra-short pulse and laser is analyzed in this paper.The structural model of EL2 trap,the characteristic of metastable energy level EL2 the distribution of EL2 in semiconductor GaAs,the measure of density and the affection of heating processing are discussed at the beginning of this paper.Based on the affection of heat endurance of material electrical parameter in the experiment,the heat endurance of electrical parameter and semiconductor character's compensation principle of semiconductor GaAs are detailed discussed in this paper.
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