Suppressing the Effect of the Wetting Layer through AlAs Capping in InAs/GaAs QD Structures for Solar Cells Applications

  1. Nazaret Ruiz 6
  2. Daniel Fernández 3
  3. Lazar Stanojevic 4
  4. Teresa Ben 3
  5. Sara Flores 3
  6. Verónica Braza 3
  7. Alejandro Gallego Carro 4
  8. Esperanza Luna 5
  9. José María Ulloa 12
  10. David González 3
  1. 1 Institute for Systems Based on Optoelectronics and Microtechnology (ISOM), Universidad Politécnica de
  2. 2 Madrid, Avda. Complutense 30, 28040 Madrid
  3. 3 University Research Institute on Electron Microscopy & Materials, (IMEYMAT), Universidad de Cádiz, 11510 Puerto Real, Spain
  4. 4 Institute for Systems Based on Optoelectronics and Microtechnology (ISOM), Universidad Politécnica de Madrid, Avda. Complutense 30, 28040 Madrid, Spain
  5. 5 Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, D-10117 Berlin, Germany
  6. 6 University Research Institute on Electron Microscopy & Materials, (IMEYMAT), Universidad de Cádiz,11510 Puerto Real, Spain
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Buch:
Advances in Nanomaterials for Photovoltaic Applications

Verlag: MDPI

ISBN: 978-3-0365-7051-8

Datum der Publikation: 2023

Seiten: 95-110

Art: Buch-Kapitel

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Zusammenfassung

Recently, thin AlAs capping layers (CLs) on InAs quantum dot solar cells (QDSCs) have been shown to yield better photovoltaic efficiency compared to traditional QDSCs. Although it has been proposed that this improvement is due to the suppression of the capture of photogenerated carriers through the wetting layer (WL) states by a de-wetting process, the mechanisms that operate during this process are not clear. In this work, a structural analysis of the WL characteristics in the AlAs/InAs QD system with different CL-thickness has been made by scanning transmissionelectron microscopy techniques. First, an exponential decline of the amount of InAs in the WL with the CL thickness increase has been found, far from a complete elimination of the WL. Instead, this reduction is linked to a higher shield effect against QD decomposition. Second, there is no compositional separation between the WL and CL, but rather single layer with a variable content of InAlGaAs. Both effects, the high intermixing and WL reduction cause a drastic change in electronic levels, with the CL making up of 1–2 monolayers being the most effective configuration to reduce the radiative-recombination and minimize the potential barriers for carrier transport.