摘要
我们用光电流谱方法在室温和低温下观察了短周期GaAs(35A)/Ga_(0.7)Al_(0.3)A_3(35A)超晶格的Wannier-Stark效应.在中等电场下,观测到了反映等能量间距的“Stark梯”的谱形.并且发观了激子态由于场致局域化导致的由准三维向准二维转变.我们详细地讨论了跃迁强度随电场的变化,与应用夏建白等提出的计算模型得出的结果十分符合,证明了光电流谱中的结构,即使在较低的 10~4V/cm的电场下是由于 Wannier局域化引起,而不可能是鞍点激子引起的.
We investigated Wannier-Stark effect of GaAs/GaAlAs superlattices under electric fieldby photocurrent measurements at room and low temperatures. At intermediate electric field, we have observed the spectral shapes of photocurrent corresponding to the evenly spaced'Stark Ladder'. We have found that the transitions of exciton state from quasi-3D to quasi-21)regime due to Wannier localization. The change of intensity of the exciton transitions withelectric field is well consistent with the theoretical calculations based on the model proposedby Xia and Huang. Our results show that the structures in the photocurrent spectra aresaused by Wannier localization instead of saddle-point excitons seven at room temperature andat relatively low field (1.0 ×10~4 V/cm).
基金
国家自然科学基金
