Femtosecond acceleration of electrons under high electric fields in bulk GaAs investigated by time-domain terahertz spectroscopy
Femtosecond acceleration of electrons under high electric fields in bulk GaAs investigated by time-domain terahertz spectroscopy
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DOI：
10.1063/1.2967857
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发表时间：
2008-08
影响因子：
4
通讯作者：
Y. M. Zhu;T. Unuma;K. Shibata;K. Hirakawa
中科院分区：
文献类型：
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作者：
Y. M. Zhu;T. Unuma;K. Shibata;K. Hirakawa
我们研究了飞秒激光脉冲在强偏置电场F下激发的未掺杂GaAs体材料的太赫兹辐射，F值可达300kVscincm。太赫兹波形中的初始正信号，通常被解释为在Γ-谷中的电子加速，被发现对于F <50kV scincm随着F的增加而增加，但是在50kV scincm以上开始逐渐减少。所观察到的行为表明，电子的有效加速质量随F的增加而显著增加。质量的增强很可能是由于在高电场下，Γ-和更高的卫星谷之间的带混合。
We have investigated terahertz emission from undoped bulk GaAs photoexcited by femtosecond laser pulses under strong bias electric fields, F, up to 300kV∕cm. The initial positive signal in the terahertz waveforms, which is usually interpreted as electron acceleration in the Γ-valley, is found to increase with increasing F for F<50kV∕cm, but to start decreasing gradually above 50kV∕cm. The observed behavior suggests that the effective acceleration mass of electrons significantly increases with increasing F. The mass enhancement is due most likely to band mixing between the Γ- and the higher satellite valleys under high electric fields.