Cross-sectional TEM (XTEM) analysis for vertically-coupled quaternary In0.21Al0.21Ga0.58As capped InAs/GaAs quantum dot infrared photodetectors

Binita Tongbram; Hemant Ghadi; Sourav Adhikary; Arjun Mandal; Subhananda Chakrabarti

doi:10.1117/12.2074835

27 February 2015 Cross-sectional TEM (XTEM) analysis for vertically coupled quaternary In_0.21Al_0.21Ga_0.58As capped InAs/GaAs quantum dot infrared photodetectors

Binita Tongbram, Hemant Ghadi, Sourav Adhikary, Arjun Mandal, Subhananda Chakrabarti

Author Affiliations +

Proceedings Volume 9373, Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling XII; 93730S (2015) https://doi.org/10.1117/12.2074835
Event: SPIE OPTO, 2015, San Francisco, California, United States

Abstract

This paper presents a detailed morphological analysis of vertically strain-coupled InAs quantum dots with a fixed quaternary capping (In_0.21Al_0.21Ga_0.58As) of 3 nm and a GaAs barrier ranging in thicknesses from 9 to 18 nm. The coupled heterostructures were studied using cross-sectional transmission electron microscopy and compared with uncoupled heterostructures with 2-nm quaternary capping and 50-nm GaAs capping thickness. Power-dependent photoluminescence spectra showed that a minimum capping of 9 nm produced a multimodal dot-size distribution. Increasing the capping from 9 to 18 nm reduced the vertical correlation, thus increasing the dot uniformity. Increasing the capping thickness reduced the coupling and increased the dot size. At a maximum capping (18nm) coupled quantum dots exhibit a bimodal dot-size distribution compared to the mono-modal distribution of the uncoupled quantum dots. The coupled samples demonstrated superior optical properties to uncoupled samples.

Citation Download Citation

Binita Tongbram, Hemant Ghadi, Sourav Adhikary, Arjun Mandal, and Subhananda Chakrabarti "Cross-sectional TEM (XTEM) analysis for vertically coupled quaternary In_0.21Al_0.21Ga_0.58As capped InAs/GaAs quantum dot infrared photodetectors", Proc. SPIE 9373, Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling XII, 93730S (27 February 2015); https://doi.org/10.1117/12.2074835

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