气源MBE外延自组装GeSi量子点光致荧光研究

利用气源分子束外延设备（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。200K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17meV。升温至200K，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129meV。

Photoluminescence study of GeSi self-assembled quantum dots grown by gas source MBE

High-brightness tapered laser diode at 850 nm was fabricated based on the AlGaInAs/A1GaAs chip with graded-index waveguide separate confinement hetero-structure. The tapered laser has better performance than the broad laser under the same condition. The lateral divergence angles of the tapered laser and the broad laser were 4° and 6° at the output power of 1w, while the beam propagation factor M2 were 2.8 and 9.2, respectively. The slope efficiency of the tapered laser had a high value of 0.58 W/A and the conversion efficiency reached 30% in the output power 1.40 W under the injection current of 3A. The facts indicated the tapered laser would be an ideal choice for high brightness high power laser diodes.