GaAsSb-capped InAs QD type-II solar cell structures improvement by composition profiling of layers surrounding QD

0484348 - FZÚ 2018 RIV GB eng J - Journal Article
Hospodková, Alice - Vyskočil, Jan - Zíková, Markéta - Oswald, Jiří - Pangrác, Jiří - Petříček, Otto
GaAsSb-capped InAs QD type-II solar cell structures improvement by composition profiling of layers surrounding QD.
Materials Research Express. Roč. 4, č. 2 (2017), s. 1-8, č. článku 025502. E-ISSN 2053-1591
R&D Projects: GA ČR(CZ) GP14-21285P; GA MŠMT(CZ) LO1603
Institutional support: RVO:68378271
Keywords : GaAsSb * InAs * InGaAs * quantum dot * solar cells * MOVPE
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 1.151, year: 2017

Type-II band alignment offers several advantages for proposed intermediate band solar cell structures. We focused on the quantum dot (QD) solar cell structures based on type-II InAs/GaAs QD layers capped with GaAsSb strain reducing layers. The GaAsSb strain reducing layers were prepared with or without graded Sb concentration. Strong enhancement of photocurrent was achieved by adding an InGaAs buffer layer under the type-II QD structure, thanks to improved electron extraction from QDs. For comparison, a structure with GaAs-capped InAs QDs was prepared, too. Properties of all structures are compared and the mechanism of carrier extraction or relaxation is discussed. Gradient of antimony concentration in a strain reducing layer (SRL) significantly improved resulting properties of solar cell structures. It is shown that in a multiple-QD structure with a GaAsSb SRL, electrons and holes have non-intersecting trajectories which prevents carrier recombination and improves the efficiency of solar cell structures. NextNano band structure calculations of different types of structures support our experimental results.
Permanent Link: http://hdl.handle.net/11104/0279501