STUDY ONTHE GROWTH PROCESS AND THE BASICPROPERTIES OF QUANTUM DOTS USING II-VI GROUP COMPOUDS

本研究通过原位监测CdSe点形成过程中的镜面光束强度，探讨了CdSe点在ZnSe上的生长机理。作为点生长方法，我们利用硒和镉的交替分子束供应（ALS）进行了分子束外延（MBE）。得到的结果如下：(1) ZnSe上的CdSe点采用Stranski-Krastanow模式生长。在ZnSe缓冲层生长的2ML CdSe上，只有第三层CdSe单层变为点。2ML-CdSe层仍为湿润层/(2)当CdSe供给低于3ML时，由于过量的Se吸附而产生CdSe点。这是ALS生长不同于理想的原子层外延（ALE）。Isp测量并没有清楚地认识到这一点。(3) CdSe点与ZnSe帽层和缓冲层的合金化。CdSe点嵌入ZnSe合金中，周围包裹着nSe，但核心部分仍为CdSe。无盖CdSe点以ZnSe为缓冲剂制成合金，整个点经过长时间的热退火成为ZnCdSe合金。(4)点的生长受倾斜角度和表面取向的强烈影响。该结果为CdSe点生成的详细分析提供了依据。

This study is to investigate the growth mechanism of CdSe dots on ZnSe by means of in-situ monitoring the specular beam intensity during the dot formation. As the dot growth method, we used the molecular beam epitaxy (MBE) using the alternate molecular beam supply (ALS) of Se and Cd. Obtained results are as follows.(1) CdSe dots on ZnSe grow by Stranski-Krastanow mode. Only the third CdSe monolayer on 2ML CdSe grown on ZnSe buffer layer changes to dot. 2ML-CdSe layer remains as a wetting layer/(2)The CdSe supply below 3ML gives rise CdSe dots, which is due to the excess Se adsorption. That is ALS growth differs from ideal atomic layer epitaxy (ALE). This is not clearly appreciated by Isp measurement.(3) The alloying of CdSe dots with ZnSe cap layer and buffer layer. CdSe dots embedded in ZnSe alloys with surrounding nSe, but the core part remains as CdSe. Capless CdSe dot makes alloy with ZnSe- buffer, and the entire dot become ZnCdSe alloy after long thermal annealing.(4) The dot growth is strongly affected by the tilt angle and surface orientation. This result give an information for the detailed analyses of CdSe dot generation.