Nonlinear dynamics of impurity states in semiconductors driven by intense THz pulses

强太赫兹脉冲驱动的半导体中杂质态的非线性动力学

• 批准号: 411486076
• 负责人: Professor Dr. Hartmut G. Roskos
• 金额: --
• 依托单位: Physikalisches Institut
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/411486076?language=en
• 关键词: Nonlinear; dynamics; impurity; states; semiconductors

Shallow dopant impurities, which provide the mobile charges in room-temperature semiconductors devices, take on a new role at low temperature, where the excess charges are instead bound to their parent ions with a set of states analogous to gas-phase atoms.Besides their potential for quantum information technology, such “quasi-atoms” can offer a unique platform for studying intense light-matter interactions, bridging the gap between high-field ultrafast phenomena in free atoms and bulk semiconductors.Due to the strong interaction with the host lattice, the photon energy scale of the impurity states is shifted from the ultraviolet (for gas atoms) down to the terahertz (THz) range, with binding fields of kV/cm and spatial extent of several nanometers. Moreover, the impurity states depend on both dopant and host species, resulting in a whole family of quasi-atoms with orbital and spin densities which deviate from a simple hydrogen model. The host interactions also confront key aspects in solid-state physics, such as the effect of phonon interactions, which have a profound effect on the lifetimes and dephasing of the excited states.Here we employ experiments with intense THz pulses to study of the non-linear response of donor/acceptor impurities in conventional semiconductor hosts (Si, Ge, GaAs).Two key phenomena can be observed: (i) the dynamic Stark (Autler-Townes) effect and quantum interference between states, and (ii) higher-harmonic generation (HHG) following tunnel ionization due to the subsequent acceleration of carriers in the THz field.Here we employ a complementary approach with both single-cycle THz pulses (in our laboratory) and multi-cycle THz pulses (in free-electron-laser facilities). The multi-cycle pulses allow a more conventional state-selective excitation and a system that can be described in terms of field-dressed (Floquet) states, whereas broadband excitation with single-cycle pulses allows one to measure the ultrafast evolution directly in the time domain and to probe for propagation effects. It also opens the possibility to control the resulting quantum state via pulse shaping.The experiments also further the application of four-wave-mixing pump-probe methodology in the THz range to the study of quantum systems, which has only recently become accessible with femtosecond laser systems. While the HHG observed from such impurities has its origin in the ionization of bound states and the emission is due to the subsequent acceleration of the carriers, analogous to the situation studied intensely for gas-phase atoms, the acceleration takes place in the adjacent semiconductor band(s), as per recent studies of HHG in bulk semiconductors with intense mid-infrared excitation. Our experimental findings will hence further unify these two existing fields.

在室温半导体设备中提供移动电荷的浅掺杂杂质在低温下扮演新角色，在这种情况下，多余的电荷与其母离子束缚在其母离子的情况下，一组类似于气相原子的状态类似于量子的潜力。在游离原子和散装半导体中，与宿主晶格的强相互作用，杂质状态的光子能尺度从紫外线（对于气体原子）向下移动到Terahertz（THz）范围，具有KV/CM的结合场，kV/cm的结合场和几个纳米图的空间范围。此外，杂质状态均取决于掺杂剂和宿主物种，从而导致整个准原子家族具有轨道和自旋密度，它们偏离了简单的氢模型。宿主的互动还面临着固态物理学的关键方面，例如声子相互作用的影响，这对激发态的生命和消化具有深远的影响。在这里，我们具有强烈的Thz脉冲的员工实验，以研究供体/接受者在传统半导体中的非线性反应中的非线性反应（geaS）（geaas peacemention ge，geaas）。由于随后在THZ场中载体的加速度加速，我们采用单个循环THZ脉冲（在我们的实验室中）和多循环脉冲脉动脉动脉动脉动（In fuls fuls interion-fluse fluse-intres fore compecibily-inthe），在我们实验室和多循环脉冲脉冲脉冲上（Quels fuls interythe fuls interionthe In fuls interive fore cyerthe intherthe Inthz pulsy-cysection），动态的静止（自动镇）效应和状态之间的效应和（ii）隧道电离后高谐波产生（HHG）的效果和量子干扰。传统的状态选择性兴奋和可以用野外（Floquet）状态描述的系统，而具有单周期脉冲的宽带兴奋使人们可以直接在时域中测量超快进化并探测传播效应。它还开放了通过脉冲成型控制所得量子状态的可能性。实验还进一步进一步应用了四波混合泵浦探针方法在THZ范围内的量子系统研究中，该方法直到最近才通过飞秒激光系统才能访问。 While the HHG observed from such impurities has its origin in the ionization of bound states and the emission is due to the subsequent acceleration of the carriers, analogous to the situation studied strongly for gas-phase atoms, the acceleration takes place in the adjacent semiconductor band(s), as per recent studies of HHG in bulk semiconductors with intense mid-infrared excitement.因此，我们的实验发现将进一步统一这两个现有领域。