Bilayer self-assembled InAs QD using digital alloy capping layer approach: experiment and theory

Ravindra Kumar; Jhuma Saha; Debiprasad Panda; Ravinder Kumar; Sanowar Alam Gazi; Raveesh Gourishetty; Subhananda Chakrabarti

doi:10.1117/12.2568820

21 August 2020 Bilayer self-assembled InAs QD using digital alloy capping layer approach: experiment and theory

Ravindra Kumar, Jhuma Saha, Debiprasad Panda, Ravinder Kumar, Sanowar Alam Gazi, Raveesh Gourishetty, Subhananda Chakrabarti

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Proceedings Volume 11465, Low-Dimensional Materials and Devices 2020; 114651A (2020) https://doi.org/10.1117/12.2568820
Event: SPIE Nanoscience + Engineering, 2020, Online Only

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Abstract

This study presents a novel approach to enhance the photoluminescence and minimize strain in selfassembled bilayer InAs quantum dot (QDs). To obtain this approach, multi-level digital alloy capping layer (DACL) is introduced in the growth of the ternary InGaAs capping layer having different material composition, instead of conventional thick layer. A single thick 4 nm InGaAs capping on the InAs QD layers (Sample A1) is divided into four equal parts each having 1 nm thicknesses. The composition of indium (In) in strain reducing layer (SRL) in growth direction is varied from 45% to 15% for both first layer and second layer QDs (Sample D1). The experimental low temperature ground state emission wavelength for the sample A1 and sample D1 was 1096 and 1167 nm respectively. The biaxial and hydrostatic strain in growth direction was theoretically computed and compared for both analog and digital samples. The computed hydrostatic and biaxial strain in sample D1 is improved by 7.19% and 6.79% respectively, when compared to that of analog sample A1. The improved hydrostatic strain provides the better carrier confinement. The improved biaxial strain offers more band splitting between heavy-hole and light-hole band in valence band. This decreases the ground state band gap and thus offers a red shift in photoluminescence (PL). The experimental PL for both samples were also validated by simulating both heterostructures. The sample with DACL growth mode provided better crystalline quality, enhanced quantum yield and lesser defects.

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Ravindra Kumar, Jhuma Saha, Debiprasad Panda, Ravinder Kumar, Sanowar Alam Gazi, Raveesh Gourishetty, and Subhananda Chakrabarti "Bilayer self-assembled InAs QD using digital alloy capping layer approach: experiment and theory", Proc. SPIE 11465, Low-Dimensional Materials and Devices 2020, 114651A (21 August 2020); https://doi.org/10.1117/12.2568820

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