Basic Research on Semiconductor Lasers with Vertical Microcavity

已经执行了各种技术方法来制造量子点结构，其对于光电器件应用和基础物理学具有潜在的有用性[1]。其主要目标之一是在纳米结构和微腔中操纵电子和光子。为了实现这一目标，重要的是发展纳米纤维和纳米尺度的光学表征技术。在这个项目中，我们研究了用于下一代半导体激光器的应变量子线和量子点。首先，我们证明了使用MOCVD生长中形成的多原子台阶结构的InGaAs量子点的自发对准[6]。在该技术中，首先，在适当的生长条件下，在相邻GaAs衬底上生长出沿沿着直线的多原子台阶GaAs外延层。然后利用应变效应在多原子台阶边缘选择性生长InGaAs量子点。这种生长技术在生长前不需要任何预处理，就可以得到自发取向的InGaAs量子点。第二，我们最近成功地制备了具有垂直微腔的量子线激光器。采用选择性生长技术制备了微腔内的量子线激光器。在微腔中，三角形形状的In 0.3Ga 0.7As应变量子线生长在[011]取向的GaAs三角棱镜的（111）A面之间，选择性地生长在SiO2掩蔽的DBR反射镜区域上。由于GaAs和In_（0.3）Ga_（0.7）As的晶格常数不同，量子线的应变比较大。通过测量有无微腔的光致发光证实了腔效应。与没有腔的样品相比，从具有微腔的量子线观察到更尖锐的光致发光光谱线。利用光抽运方法，在77K下观察到了该样品的激光振荡。

Various technological approaches have been performed to fabricate quantum dot structures which are potentially useful for optoelectronic device application and basic physics [1]. One of main goals is to manipulate both electrons and photons in nanostructures and microcavities. Towards this goal, it is important to develop nanofabrication and nano-scale optical characterization techniques. In this project, we investigate strained quantum wires and quantum dots for the semiconductor lasers of the next generation.First, we demonstrated spontaneous alignment of InGaAs quantum dots using multi-atomic step structures formed in MOCVD growth [6]. In this technique, first, GaAs epilayr with multi-atomic steps along straight lines was grown on vicinal GaAs substrate under appropriate growth conditions. Then the InGaAs quantum dots were grown selectively on the multi-atomic step edges using strain effects. This growth technique results in spontaneously aligned InGaAs quantum dots without any pre-processing technique prior to the growth.Second, we recently succeeded in fabricating quantum wire laser with vertical microcavity. The quantum wire laser inside the microcavity was fabricated using the selective growth technique. In the microcavity, triangular-shaped In0.3Ga0.7As strained quantum wires are grown between (111)A facets of [011]-oriented GaAs triangular prisms selectively grown on a SiO2 masked DBR mirror region. The quantum wires are comparatively strained owing to the difference of the lattice constants of GaAs and In0.3Ga0.7As. The cavity effect is confirmed by measuring photoluminescence with and without the microcavity. A much sharper photoluminescence spectral line was observed from the quantum wires with the microcavity compared to the sample without the cavity. The lasing oscillation of this sample was demonstrated at 77K,using optical pumping method.