Ma Yingjie, Zhong Zhenyang, Lv Quan, Qiu Weiyang, Wang Xinjun, Zhou Tong, Fan Yongliang, Jiang Zuimin
State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures Ministry of Education and Department of Physics, Fudan University, Shanghai 200433, China.
Opt Express. 2013 Mar 11;21(5):6053-60. doi: 10.1364/OE.21.006053.
We report on optical properties of coupled three-dimensional (3D) Ge quantum dot crystals (QDCs). With increasing the vertical periodic number of the QDCs, the photoluminescence (PL) spectral linewidth decreased exponentially, and so did the peak energy blueshift caused by increasing excitation power, which are attributed to the electronic coupling and thus the formation of miniband. In the PL spectra, the relative intensity of the transverse-optical (TO) phonon replica also decreases with increasing the vertical periodic number, which is attributed to the increased Brillouin-zone folding effect in vertical direction and therewith the relaxation of indirect transition nature of exciton recombination. Besides, the optical reflectivity at the interband transition energy was much more reduced for the QDCs than for the in-plane disordered QDs grown with the same parameters, indicating a higher interband absorption of the QDCs due to the miniband formation.
我们报道了耦合三维（3D）锗量子点晶体（QDCs）的光学性质。随着QDCs垂直周期数的增加，光致发光（PL）光谱线宽呈指数下降，由激发功率增加引起的峰值能量蓝移也如此，这归因于电子耦合以及因此形成的微带。在PL光谱中，横向光学（TO）声子复制品的相对强度也随着垂直周期数的增加而降低，这归因于垂直方向上布里渊区折叠效应的增加以及激子复合间接跃迁性质的弛豫。此外，与以相同参数生长的面内无序量子点相比，QDCs在带间跃迁能量处的光学反射率降低得更多，这表明由于微带的形成，QDCs具有更高的带间吸收率。
