【摘要】 用低压金属有机化学气相外延(LP MOCVD)技术,以Stranski Krastanow(S K)模式,在GaAs衬底上生长了CdSe和ZnCdSe量子点(QDs)。用原子力显微镜(AFM),观测到了外延层低于临界厚度时,CdSe自组装量子点的形成过程,并把其机理归结为表面扩散效应和应变弛豫效应的联合作用。依据理论计算外延层临界厚度值的指导,用LP MOCVD技术在GaAs衬底上生长了ZnCdSe量子点,详细观测了ZnCdSe量子点的形成和演变,这些过程可用Ostwald熟化过程和形成过程的联合作用来解释。用LP MOCVD技术,以Volmer Weber(V W)模式,在GaAs衬底上生长了ZnSeS量子点,随着生长时间的增加,量子点尺寸增大,而量子点密度减少,这些现象可用表面自由能来解释。更多还原

【Abstract】 CdSe self-assembled quantum dots (SAQDs) were grown on GaAs(100) by LP-MOCVD under Stranski-Krastanow(S-K) mode. Formation process of CdSe SAQDs below the critical thickness was observed by atomic force microscopy(AFM) images. It revealed that the formation of CdSe SAQDs below the critical thick was due to the effect of surface diffusion and strain release. ZnCdSe SAQDs were grown on GaAs(100) based on the calculated critical thickness by LP-MOCVD under S-K mode. Two kinds of variations in the QDs appeared over time, the Ostwald ripening process and formation process, which is interpreted by theory of crystal growth. ZnSeS QDs were grown on GaAs(100) by LP-MOCVD under V-W mode. With increasing the growth duration, the size of dots becomes larger and the density of the dots decreases, which is explained by virtue of surface free energy.更多还原