Role of InxGa1-xAs strain relaxation layers in optical and structural properties of InAs/GaAs quantum dots

Jin Dong Song; Yong Min Park; Jae Gu Lim; Jae Cheol Shin; Yong Ju Park; Won Jun Choi; Il-Ki Han; Woon-Jo Cho; Jung Il Lee

doi:10.1117/12.506478

24 November 2003 Role of In_xGa_1-xAs strain relaxation layers in optical and structural properties of InAs/GaAs quantum dots

Jin Dong Song, Yong Min Park, Jae Gu Lim, Jae Cheol Shin, Yong Ju Park, Won Jun Choi, Il-Ki Han, Woon-Jo Cho, Jung Il Lee

Author Affiliations +

Proceedings Volume 5224, Nanomaterials and Their Optical Applications; (2003) https://doi.org/10.1117/12.506478
Event: Optical Science and Technology, SPIE's 48th Annual Meeting, 2003, San Diego, California, United States

Abstract

Effects of In_xGa_1-xAs strain relaxation layers on the optical and structural properties of InAs quantum dots (QDs) were studied systemically. 300 K-photoluminescence (PL) shows that PL peak energy of the QDs is blue-shifted in GaAs/InAs QDs/5 nm-thick In_0.1Ga_0.9As structure compared to GaAs/InAs QDs/GaAs structure. This is attributed to the intermixing of materials between the QDs and the InGaAs layer below the QDs, whereas capping of a 5 nm-thick In_0.1Ga_0.9As layer leads to red shift due to strain relaxation effect. As thickness of In_xGa_1-xAs capping layer (TI) increases, 300 K-PL peaks experience red shift below TI < ~7 nm. Unlikely, TI above 7 nm results in blue shift. Considering average height of the QDs is ~ 7 nm, this is attributed to intermixing of material between the QDs and InGaAs capping layers. The blue shift in x = 0.2 over TI > ~7 nm is relatively smaller compared to that in x = 0.1. It is noteworthy that strain difference between the InAs QDs and the In_xGa_1-xAs is smaller in x = 0.2 rather than in x = 0.1. Finally, InAs QDs are sandwiched by asymmetric thickness (7.5 nm-thick capping InGaAs, 0, 1.2, and 2.5 nm-thick bottom InGaAs) of In_0.2Ga_0.8As layers. 300 K-PL spectrum shows that 1.2 nm-thick bottom InGaAs leads to the longest wavelength (1306 nm) among this sample set. This is attributed to reduced barrier height and ignorable accumulated strain effect in thin bottom InGaAs layers. In this report, we justify merit of dots in an asymmetric well structure over conventional dots in a symmetric well structure and strain relaxation structure for the control of PL peak energy.

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Jin Dong Song, Yong Min Park, Jae Gu Lim, Jae Cheol Shin, Yong Ju Park, Won Jun Choi, Il-Ki Han, Woon-Jo Cho, and Jung Il Lee "Role of In_xGa_1-xAs strain relaxation layers in optical and structural properties of InAs/GaAs quantum dots", Proc. SPIE 5224, Nanomaterials and Their Optical Applications, (24 November 2003); https://doi.org/10.1117/12.506478

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