Identification of the Segregation Kinetics of Ultrathin GaAsSb/GaAs Films Using AlAs Markers

For optoelectronic devices from the near to the far infrared, the advantages of using ultrathin III-Sb layers as quantum wells or in superlattices are well known. However, these alloys suffer from severe surface segregation problems, so that the actual profiles are very different from the nominal on...

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Bibliographic Details
Published in:Nanomaterials (Basel, Switzerland) Switzerland), 2023-02, Vol.13 (5), p.798
Main Authors: Gonzalez, David, Flores, Sara, Braza, Verónica, Reyes, Daniel F, Carro, Alejandro Gallego, Stanojević, Lazar, Schwarz, Malte, Ulloa, Jose María, Ben, Teresa
Format: Article
Language:English
Subjects:
Alloys
Aluminum arsenides
III-Sb alloys
Molecular beam epitaxy
Optoelectronic devices
Phase transitions
Quantum dots
Quantum wells
segregation
STEM analyses
Superlattices
Transmission electron microscopy
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Summary:For optoelectronic devices from the near to the far infrared, the advantages of using ultrathin III-Sb layers as quantum wells or in superlattices are well known. However, these alloys suffer from severe surface segregation problems, so that the actual profiles are very different from the nominal ones. Here, by inserting AlAs markers within the structure, state-of-the-art transmission electron microscopy techniques were used to precisely monitor the incorporation/segregation of Sb in ultrathin GaAsSb films (from 1 to 20 monolayers (MLs)). Our rigorous analysis allows us to apply the most successful model for describing the segregation of III-Sb alloys (three-layer kinetic model) in an unprecedented way, limiting the number of parameters to be fitted. The simulation results show that the segregation energy is not constant throughout the growth (which is not considered in any segregation model) but has an exponential decay from 0.18 eV to converge asymptotically towards 0.05 eV. This explains why the Sb profiles follow a sigmoidal growth model curve with an initial lag in Sb incorporation of 5 MLs and would be consistent with a progressive change in surface reconstruction as the floating layer is enriched.
ISSN:2079-4991
2079-4991
DOI:10.3390/nano13050798