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利用飞秒光电导自相关技术研究了LT GaAs飞秒光电导开关时间随外加偏置电场的变化规律 .实验结果显示当外加偏置电场从 0 5× 1 0 4 V cm上升到 9 5× 1 0 4 V cm时 ,光电导开关时间开始在 2 0 0fs附近缓慢变化再迅速增加到 75 0fs.这是由于随着外加电场增加 ,Frenkel Poole效应导致的EL2缺陷中心库仑吸引势垒降低和电场增强的碰撞电离效应显著增强 ,导致载流子俘获截面减小 ,载流子寿命增加之故
The variation law of LT GaAs femtosecond photoconductive switch with applied bias electric field was studied by femtosecond photoconductive autocorrelation technique.The experimental results show that when the applied bias electric field increases from 0 5 × 10 4 V cm to 9 5 × 1 At 0 4 V cm, the photoconductive switch time began to slowly change around 200 fs and then rapidly increased to 75 0 fs. This is due to the decrease of the Coulomb attraction barrier and the increase of the electric field due to the Frenkel Poole effect with the increase of the applied electric field Of the collision ionization effect is significantly enhanced, resulting in a reduction of carrier capture cross section, carrier lifetime increase