Self-assembled MgxZn1−xO quantum dots (0 ≤ x ≤ 1) on different substrates using spray pyrolysis methodology

Achary, Sreekumar Rajappan and Agouram, Said and Sánchez Royo, Juan Francisco and Lopez Ponce, Manuel and Ulloa Herrero, José María and Muñoz Merino, Elias and Hierro Cano, Adrián and Muñoz Sanjosé, Vicente (2013). Self-assembled MgxZn1−xO quantum dots (0 ≤ x ≤ 1) on different substrates using spray pyrolysis methodology. "CrystEngComm" (n. 15); pp. 182-191. ISSN 1466-8033. https://doi.org/10.1039/C2CE26253C.

Description

Title: Self-assembled MgxZn1−xO quantum dots (0 ≤ x ≤ 1) on different substrates using spray pyrolysis methodology
Author/s:
  • Achary, Sreekumar Rajappan
  • Agouram, Said
  • Sánchez Royo, Juan Francisco
  • Lopez Ponce, Manuel
  • Ulloa Herrero, José María
  • Muñoz Merino, Elias
  • Hierro Cano, Adrián
  • Muñoz Sanjosé, Vicente
Item Type: Article
Título de Revista/Publicación: CrystEngComm
Date: 2013
ISSN: 1466-8033
Subjects:
Faculty: E.T.S.I. Telecomunicación (UPM)
Department: Ingeniería Electrónica
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

By using the spray pyrolysis methodology in its classical configuration we have grown self-assembled MgxZn1−xO quantum dots (size [similar]4–6 nm) in the overall range of compositions 0 ≤ x ≤ 1 on c-sapphire, Si (100) and quartz substrates. Composition of the quantum dots was determined by means of transmission electron microscopy-energy dispersive X-ray analysis (TEM-EDAX) and X-ray photoelectron spectroscopy. Selected area electron diffraction reveals the growth of single phase hexagonal MgxZn1−xO quantum dots with composition 0 ≤ x ≤ 0.32 by using a nominal concentration of Mg in the range 0 to 45%. Onset of Mg concentration about 50% (nominal) forces the hexagonal lattice to undergo a phase transition from hexagonal to a cubic structure which resulted in the growth of hexagonal and cubic phases of MgxZn1−xO in the intermediate range of Mg concentrations 50 to 85% (0.39 ≤ x ≤ 0.77), whereas higher nominal concentration of Mg ≥ 90% (0.81 ≤ x ≤ 1) leads to the growth of single phase cubic MgxZn1−xO quantum dots. High resolution transmission electron microscopy and fast Fourier transform confirm the results and show clearly distinguishable hexagonal and cubic crystal structures of the respective quantum dots. A difference of 0.24 eV was detected between the core levels (Zn 2p and Mg 1s) measured in quantum dots with hexagonal and cubic structures by X-ray photoemission. The shift of these core levels can be explained in the frame of the different coordination of cations in the hexagonal and cubic configurations. Finally, the optical absorption measurements performed on single phase hexagonal MgxZn1−xO QDs exhibited a clear shift in optical energy gap on increasing the Mg concentration from 0 to 40%, which is explained as an effect of substitution of Zn2+ by Mg2+ in the ZnO lattice.

More information

Item ID: 15776
DC Identifier: http://oa.upm.es/15776/
OAI Identifier: oai:oa.upm.es:15776
DOI: 10.1039/C2CE26253C
Official URL: http://pubs.rsc.org/en/Content/ArticleLanding/2013/CE/c2ce26253c
Deposited by: Memoria Investigacion
Deposited on: 29 Jun 2013 09:14
Last Modified: 21 Apr 2016 16:04
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