Optimizations for Quaternary Alloy (InAlGaAs)-Capped InAs/GaAs Multilayer Quantum Dots
As discussed in the last chapter the effects of both light and heavy ion implantations on InAs/GaAs QDs for the ion optimization purpose, it is also necessary to select ideal In(Ga)As/GaAs QD-based heterostructures to navigate the effects of ion implantat
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Optimizations for Quaternary Alloy (InAlGaAs)-Capped InAs/GaAs Multilayer Quantum Dots
Abstract As discussed in the last chapter the effects of both light and heavy ion implantations on InAs/GaAs QDs for the ion optimization purpose, it is also necessary to select ideal In(Ga)As/GaAs QD-based heterostructures to navigate the effects of ion implantations on them, i.e. we must go for heterostructures which can produce devices with high efficiency. In this chapter, the structural and optoelectronic properties of quaternary alloy (InAlGaAs)-capped multilayer In(Ga)As/GaAs QD heterostructures were investigated by varying growth rate, capping layer thickness and seed QD monolayer coverage. We had already discussed in the first chapter the effects of capping layers over InAs QDs. In addition, when all the samples were annealed at various temperatures, the results showed that structural and optoelectronic properties are greatly influenced by annealing temperatures.
Keywords Multilayer QDs Quaternary alloy (InAlGaAs) capping Seed monolayer coverage Rapid thermal annealing (RTA) Intermediate-band-gap solar cells Multimodal QDs
Portions of this chapter is reprinted from 1. A. Mandal et al., “Thermal stability of quaternary alloy (InAlGaAs)-capped InAs/GaAs multilayer quantum dot heterostructures with variation in growth rate, barrier thickness, seed quantum dot monolayer coverage, and post-growth annealing”, Applied Physics A Materials Science & Processing (DOI 10.1007/s00339-0127521-2), 2. A. Mandal et al., “The impact of monolayer coverage, barrier thickness and growth rate on the thermal stability of photoluminescence of coupled InAs/GaAs quantum dot hetero-structure with quaternary capping of InAlGaAs” Materials Research Bulletin, Vol. 47, pp. 551–556, 2012, 3. A. Mandal et al., “Effects of ex situ annealing on quaternary alloy (InAlGaAs) capped InAs/GaAs quantum dot heterostructures on optimization of optoelectronic and structural properties with variation in growth rate, barrier thickness, and seed quantum dot monolayer coverage,” Superlattices and Microstructures, Vol. 58, pp. 101–119, 2013, with permission from Elsevier. © Springer Nature Singapore Pte Ltd. 2017 A. Mandal and S. Chakrabarti, Impact of Ion Implantation on Quantum Dot Heterostructures and Devices, DOI 10.1007/978-981-10-4334-5_3
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Motivation Behind the Study
After we established in previous chapter that low energy light ion implantation could enhance the material properties of single-layer InAs/GaAs QDs, our immediate focus was to validate these improvements in case of In(Ga)As/GaAs QD-based device structures, i.e. to check whether low energy light ion implantation could improve device performance. Another significant aspect of our study, as mentioned earlier, was to introduce quaternary alloy (InAlGaAs) capping over the dots to improve QD characteristics. We studied quaternary alloy-capped InAs/GaAs multilayer quantum dots (MQDs) in this chapter from both these viewp
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