气源MBE外延自组装GeSi量子点的光致荧光

Photoluminescence of GeSi Self-assembled Quantum Dots Grown by Gas Source MBE

利用气源分子束外延技术(MBE)制作了GeSi自组装量子点样品。利用原子力显微镜(AFM)和光致荧光(PL)光谱研究了该量子点的形貌和光学性质。气源MBE在较低温度下生长的量子点材料具有较高的量子点覆盖度。200 K以下载流子以局域激子形式束缚在量子点中,激子束缚能约为17 meV。升温至200 K,载流子的输运过程发生变化。对量子点PL积分强度与温度关系曲线进行拟合得到量子点中空穴跃迁至浸润层的热激活能为129 meV。

Self-assembled GeSi quantum dots（QDs） were grown by gas source molecular beam epitaxy（MBE）.Morphology and optical properties of the QDs were studied by atomic force microscopy（AFM） and photoluminescence（PL） spectra.QDs structure grown by gas source MBE at lower temperature showed a higher QDs coverage,lower defect and impurity density.Below 200 K,carriers are trapped in QDs as excitons with bonding energy of about 17 meV.The transport process changes as increasing the temperature to 200 K.By fitting the temperature dependence curves of PL integrated intensity,the activation energy of 129 meV representing the energy difference between the wetting layer and QDs was obtained.