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2 March 2020 Submonolayer quantum dots in P-i-P configuration: study on effects of monolayer coverage and stacking variations
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Submonolayer (SML) quantum dots (QDs) have higher confinement than conventional Stranski- Krastanov (SK) QDs. Moreover, hole-transport based QD infrared photodetectors (QDIPs) are anticipated to perform better at a higher temperature than its counterparts (electron-transport based devices). Effects of different stacking configuration and monolayer (ML) coverage of InAs SML QDs in In0.15Ga0.85As matrix are studied here for the development of high temperature operable, hole-transport based QDIPs. We increased the number of dot layers in the matrix as 4, 6 and 8. The monolayer coverage is varied from 0.3 ML to 0.5 ML. Radiative recombination is captured by photoluminescence (PL) and PL excitation (PLE) to observe the energy states of the grown heterostructures. The PL results in case of 0.3ML QDs show a gradual red shift in the ground state (GS) emission when we stack more dot layers in the matrix (1.334 eV, 1.269 eV, and 1.244 eV). Increase in dot size is suspected as the reason behind this change. A decrease in the difference between GS and first excited state (ES1) confirms the enlargement of dots for these samples. However, the PL (multimodal) peak position with maximum intensity changes more interestingly (1.195 eV, 1.154 eV and 1.188 eV) for 0.5 ML QDs with the increase in stacking. This variation is expected to be associated with the relaxation of dots via out diffusion of In atoms from the dot.
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Suryansh Dongre, Debiprasad Panda, Sanowar Alam Gazi, Debabrata Das, Ravinder Kumar, Nivedita Pandey, Abhishek Kumar, and Subhananda Chakrabarti "Submonolayer quantum dots in P-i-P configuration: study on effects of monolayer coverage and stacking variations", Proc. SPIE 11291, Quantum Dots, Nanostructures, and Quantum Materials: Growth, Characterization, and Modeling XVII, 112910Q (2 March 2020);

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