Manipulation of the structural and optical properties of InAs quantum dots by using various InGaAs structures

• Published in: Journal of applied physics Vol. 94; no. 10; pp. 6603 - 6606
• Main Authors: Kim, Jin Soo, Lee, Jin Hong, Hong, Sung Ui, Han, Won Seok, Kwack, Ho-Sang, Lee, Chul Wook, Oh, Dae Kon
• Format: Journal Article
• Language: English
• Published: 15.11.2003
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.1621714

The structural and optical properties of self-assembled InAs quantum dots (QDs) with various InGaAs structures were investigated by transmission electron microscopy (TEM) and photoluminescence (PL). The emission peak position of InAs QDs covered by a 6 nm In0.15Ga0.85As layer was 1.26 μm with PL linewidth of 31 meV, which is narrower than that of QDs in a GaAs matrix. By inserting a 1 nm In0.15Ga0.85As layer below the InAs QD layer with a 6 nm In0.15Ga0.85As overgrowth layer, the emission peak position was redshifted with larger energy-level spacing between the ground states and the first excited states compared to that of QDs with an In0.15Ga0.85As overgrowth layer only. By covering the InAs QDs on a 1 nm In0.15Ga0.85As layer with an 8 nm InxGa1−xAs layer having graded In composition, the emission peak position was 1.32 μm with relatively larger energy-level spacing and narrower PL linewidth compared to QDs covered by an In0.15Ga0.85As layer. The longer emission wavelength with relatively larger energy-level spacing was largely related to the change in the QD shape and size, especially the aspect ratio (height/width), which was confirmed by cross-sectional TEM images.