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Issue 21, 2012
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Electronic structure and band gap engineering of CdTe semiconductor nanowires

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Abstract

The structural and electronic properties of (10[1 with combining macron]0) faceted CdTe nanowires with hexagonal or triangular cross sections were investigated using the self-consistent-charge density-functional tight-binding (SCC-DFTB) method. The formation energies and band gap of CdTe nanowires are studied as a function of both nanowire size and surface atom ratio. The atomic relaxations of the surface of the (10[1 with combining macron]0) CdTe nanowires are compared with the corresponding (10[1 with combining macron]0) CdTe surface. The surface strain was eliminated by passivating the dangling bonds with hydrogen atoms. The passivation of the dangling bonds has only little influence on the band gap resulting only in an increase of about 0.06 eV as compared to unpassivated nanowires. However, it had a significant influence on the highest occupied molecular orbital (HOMO) and the lowest unoccupied orbital (LUMO). We also investigated the effect of the adsorption of dicarboxylic acid derivatives on the (10[1 with combining macron]0) surface of the hexagonal unpassivated CdTe nanowire with a goal to engineer the band gap. From the band alignment we conclude that the hybrid systems NW-DCDC (di-cyano di-carboxylic acid) and NW-DNDC (di-nitro di-carboxylic acid) represent a type II surface characterized by the presence of molecular states in the gap which reduce the optical gap and may be suitable for use in nanowire-dye sensitized solar cells.

Graphical abstract: Electronic structure and band gap engineering of CdTe semiconductor nanowires

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Article information


Submitted
23 Dec 2011
Accepted
29 Mar 2012
First published
19 Apr 2012

J. Mater. Chem., 2012,22, 10716-10724
Article type
Paper

Electronic structure and band gap engineering of CdTe semiconductor nanowires

S. Sarkar, S. Pal and P. Sarkar, J. Mater. Chem., 2012, 22, 10716
DOI: 10.1039/C2JM16810C

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