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Improved device performances based on Si quantum dot/Si nanowire hetero-structures by inserting an Al2O3 thin layer

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Abstract

Si quantum dot-based light emitting devices were fabricated on Si nanowire arrays in order to improve light extraction efficiency. However, the device performance is deteriorated by using Si nanowires with a depth of 1.2 μm due to serious surface recombination. By introducing an Al2O3 thin layer between the Si quantum dots and Si nanowires, significantly enhanced electroluminescence (∼8.5 fold) has been demonstrated. Based on electron spin resonance, capacitance–voltage and conductance–voltage measurements, the effect of the Al2O3 thin layer on the improvement of device performance is quantitatively evaluated. Our results demonstrate that besides the chemical passivation to reduce the surface defect states of Si nanowires, the Al2O3 thin layer can act as a barrier layer to confine the injected carriers in the active Si quantum dot layer due to the existence of negatively fixed charges and a potential barrier. As a consequence, radiative recombination is promoted which contributes to the enhanced light emission from devices based on Si quantum dot/Si nanowire hetero-structures.

Graphical abstract: Improved device performances based on Si quantum dot/Si nanowire hetero-structures by inserting an Al2O3 thin layer

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Publication details

The article was received on 02 Aug 2017, accepted on 22 Sep 2017 and first published on 22 Sep 2017


Article type: Paper
DOI: 10.1039/C7NR05694J
Citation: Nanoscale, 2017, Advance Article
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    Improved device performances based on Si quantum dot/Si nanowire hetero-structures by inserting an Al2O3 thin layer

    Y. Ji, Y. Zhai, H. Yang, J. Liu, W. Shao, J. Xu, W. Li and K. Chen, Nanoscale, 2017, Advance Article , DOI: 10.1039/C7NR05694J

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