We investigate peculiar Bloch oscillations under interminiband mixing in a GaAs-based narrow-minigap superlattice by terahertz emission spectroscopy. The dephasing time decreases with increasing pump photon energy and drops substantially at a certain energy, in contrast to that reported for Wannier–Stark ladder states in a nearly isolated miniband. This behavior can be ascribed to the LO phonon emission of electrons that are excited with in-plane excess energies and accelerated under dc bias electric field in the conduction first miniband. Our findings support the validity of the miniband transport model employed recently to account for an accompanying π/2 shift in the oscillation phase.

我们通过太赫兹发射光谱研究了基于 GaAs 的窄小间隙超晶格中小带间混合下的特殊 Bloch 振荡。相移时间随着泵浦光子能量的增加而减少，并在某个能量下显着下降，这与几乎孤立的微带中 Wannier-Stark 梯形状态的报道相反。这种行为可以归因于电子的 LO 声子发射，这些电子被面内过剩能量激发并在传导第一微带中的直流偏置电场下加速。我们的研究结果支持了最近用于解释振荡相位中伴随的π /2 偏移的微型带传输模型的有效性。