Electronic states and luminescence in higher fullerene/porous Si nanocrystal composites

Wu, X. L.; Deng, Zh H.; Xue, F. S.; Siu, G. G.; Chu, Paul K.

doi:10.1063/1.2202742

Cited by 2 publications

(3 citation statements)

References 21 publications

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“…Soon after the demonstration of strong photoluminescence (PL) in nanostructured porous silicon [1], much effort has been devoted to elaborate silicon-based nanocomposite structures [2][3][4][5][6][7][8], either to realize multi-band emissions or to improve the PL stability and efficiency of the substrates. For example, copper [9], diamond [10], fullerene [11], Pb(Zr x , Ti 1−x )O 3 (PZT) [12], ZnSe [13], ZnS [14,15], ZnO [16,17], CdSe [18] and CdS [19][20][21][22] have been used as components to fabricate silicon-based nanocomposite structures, and unique optical properties have been achieved in these systems. As one of the promising II-VI compound semiconductors, cadmium sulfide (CdS) has been found to possess the properties of high electrical conductibility, broad-spectrum light transparency and high chemical stability [23][24][25][26][27][28], and has been much considered for potential applications in the fields of solar cells [23], optoelectronics [24][25][26] and microelectronics [27].…”

Section: Introductionmentioning

confidence: 99%

Preparation, structural and photoluminescent properties of CdS/silicon nanoporous pillar array

Xu¹,

Li²

2007

J. Phys.: Condens. Matter

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A silicon nanoporous pillar array (Si-NPA) is a silicon hierarchical structure with regularly patterned surface morphology. Through a heterogeneous reaction process, nanocrystallites of cadmium sulfide (nc-CdS) were grown onto Si-NPA and a uniquely patterned nanocomposite structure (CdS/Si-NPA) was obtained. The nc-CdS, whose average size was evaluated to be ∼25 nm, mainly grew at two typical sites of the Si-NPA. One was the top sites of the porous pillars where nc-CdS clusters were formed, and the other was the valley sites surrounding the porous pillars where nc-CdS rings were formed. The nc-CdS was proved to be separated from the Si-NPA substrate by a thin layer of SiO 2 with a thickness of ∼1.3 nm. In addition to the two red photoluminescence (PL) bands observed in the Si-NPA, a green PL band peaked at ∼495 nm was observed in CdS/Si-NPA when it was excited by 370 nm wavelength ultraviolet light. Based on these experimental results, the green and red PL bands of CdS/Si-NPA were attributed to the radiative recombination of the excitons occurring in nc-CdS and Si-NPA separately.

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Section: Introductionmentioning

confidence: 99%

Preparation, structural and photoluminescent properties of CdS/silicon nanoporous pillar array

Xu¹,

Li²

2007

J. Phys.: Condens. Matter

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“…By measuring the friction force versus applied force for the Si (001) surface, it was shown that the friction coefficient is decreased for more than one order of magnitude, while silicon surface is covered by a C 60 thin film. There are some experimental works devoted to investigation of C 60 molecules implanted in porous silicon. − In ref the authors observed an enhanced photoluminescence (PL) signal, in addition to the PL peak of porous Si, a peak at 730 nm caused by perfect C 60 molecules and other peaks at 620 and 630 nm caused by imperfect C 60 molecules. In the same work, unusual Raman features related to the C 60 molecular environments and disorder effects inside solid silicon were obtained with large intensities.…”

Section: Introductionmentioning

confidence: 99%

“…There are some experimental works devoted to investigation of C 60 molecules implanted in porous silicon. [6][7][8] In reference 6 the authors observed an enhanced photoluminescence (PL) signal, in addition to the PL peak of porous Si, a peak at 730 nm caused by perfect C 60 molecules and other peaks at 620 and 630 nm caused by imperfect C 60 molecules. In the same work, unusual Raman features related to the C 60 molecular environments and disorder effects inside solid silicon were obtained with large intensities.…”

Section: Fullerenes Possess Unique Mechanical Properties Chemical Inmentioning

confidence: 99%

Theoretical Investigation of Molecular and Electronic Structures of Buckminsterfullerene-Silicon Quantum Dot Systems

et al. 2016

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Theoretical simulations of embedding and relaxation of buckminsterfullerene C 60 molecules chemisorbed on representative surfaces and inside a bulk silicon lattice were performed using both the generalized gradient density functional theory (GGA-DFT) and the self-consistent-charge density-functional tight-binding (DFTB) molecular dynamics (DFTB/MD) methods. We chose fullerene molecules as representative models for general quantum dots on the surface or inside bulk a semiconductor, in this case silicon. If a single C 60 molecule is chemisorbed on (001) and (111) silicon slab surfaces, static GGA-DFT calculations show that the C 60 molecule deformation was very small and the C 60 binding energies were roughly around 4 eV. In these configurations, the analysis of the charge distributions shows that the charge of C 60 molecules on the (001) and (111) silicon surfaces was only between -2 to -3.5 electrons, respectively, that is correlates well with number of C-Si bonds linking the fullerene molecule and the silicon surface. On the other hand, static  Current address: Atotech Deutschland GmbH, 10553 Berlin, Germany GGA-DFT calculations of C 60 molecule relaxation inside suitable hollow spheres in the bulk silicon were performed. After the silicon bulk-C 60 system relaxation, we investigated electronic density of states (DOS), partial DOS and charge distribution. These calculations confirm that the C 60 molecule remains stable inside bulk silicon having deformation energy values of between 11 and 15 eV for geometries with different rotational C 60 configurations, respectively. Formation of some C-Si bonds cause local silicon amorphization and corresponded electronic charge uptake on the embedded fullerene cages. According to еру charge analysis, these quantum dots can accept up to 20 excess electrons, wherein while the main charge contribution is located on the carbon atom bonded to silicon atoms. The dynamic embedding process was modeled using the DFTB/MD method by placing a C 60 molecule on top of a Si (111) slab surface and further exposition to a stream of silicon dimers with kinetic energies equivalent to a temperature of ~723 K directed to the C 60 -silicon surface. After the final MD shot, the resulting geometry was fully relaxed. These calculations show that during landing of the C 60 molecule on the silicon surface and subsequent overgrowth by silicon, C 60 molecule remains stable inside bulk silicon, wherein the C 60 molecule adopts a deformation energy of about 17.8 eV and the overgrowth process leads to a local silicon amorphization, in qualitatively good agreement with the static GGA-DFT calculations.

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Electronic states and luminescence in higher fullerene/porous Si nanocrystal composites

Cited by 2 publications

References 21 publications

Preparation, structural and photoluminescent properties of CdS/silicon nanoporous pillar array

Preparation, structural and photoluminescent properties of CdS/silicon nanoporous pillar array

Theoretical Investigation of Molecular and Electronic Structures of Buckminsterfullerene-Silicon Quantum Dot Systems

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