应力导致InAs/In_(0.15)Ga_(0.85)As量子点结构中In_(0.15)Ga_(0.85)As阱层的合金分解效应研究

Strain-driven alloy decomposition of In_(0.15)Ga_(0.85)As well layers in InAs/In_(0.15)Ga_(0.85)As dots-in-a-well structure

利用固源分子束外延技术,在In0.15Ga0.85As/GaAs量子阱生长了两个InAs/In0.15Ga0.85As量子点(DWELL)样品.通过改变其中一个InAsDWELL样品中的In0.15Ga0.85As阱层的厚度和生长温度,获得了量子点尺寸增大而且尺寸分布更均匀的结果.结合光致发光光谱(PL)和压电调制光谱(PzR)实验结果,发现该样品量子点的光学性质也同时得到了极大的优化.基于有效质量近似的数值计算结果表明:量子点后生长过程中应力导致In0.15Ga0.85As阱层合金分解机理是导致量子点尺寸和光学性质得到优化的主要原因.

Two InAs/In 0.15 Ga 0.85 As quantum dots-in-a-well （DWELL） samples have been grown by solid source molecular beam epitaxy （MBE）. The increased size of InAs dots and more homogeneous dot-size distribution have been found in one InAs DWELL sample with growth optimized by changing both the growth temperature and the thickness in In 0.15 Ga 0.85 As well layers. The improved optical properties of this sample have also been confirmed by photoluminescence （PL） and piezomodulated reflectance （PzR） spectra. The numerical calculations based on effective mass approximation indicate that the increase of dot size and the improved optical properties are dominantly due to the strain driven alloy decomposition of In（0.15）Ga（0.85）As well layers.