Doping efficiency of phosphorus doped silicon nanocrystals embedded in a SiO2 matrix

Gutsch, Sebastian; Härtel, Andreas; Hiller, Daniel; Zakharov, N. D.; Werner, P.; Zacharias, Margit

doi:10.1063/1.4727891

Cited by 38 publications

(33 citation statements)

References 24 publications

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“…2b ) which cover SiNCs with a thickness of 1 to 1.5 mono layers (MLs) 28 . This finding is supported by PL quenching reported for high P concentrations mentioned above 3 29 .…”

Section: Resultssupporting

confidence: 84%

“…P located within SiNCs or within SiO x shells around SiNCs are deep defect centers which appear to provide the most efficient and fastest path for non-radiative carrier recombination. This process explains PL quenching already at reasonably high P densities 29 still below values reported elsewhere 3 4 . Co-doping with B was shown in experiment to PL intensities while transition energies decreased below those of undoped SiNCs 3 .…”

Section: Discussionmentioning

confidence: 57%

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Location and Electronic Nature of Phosphorus in the Si Nanocrystal − SiO2 System

König

Gutsch

Gnaser

et al. 2015

Sci Rep

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Up to now, no consensus exists about the electronic nature of phosphorus (P) as donor for SiO2-embedded silicon nanocrystals (SiNCs). Here, we report on hybrid density functional theory (h-DFT) calculations of P in the SiNC/SiO2 system matching our experimental findings. Relevant P configurations within SiNCs, at SiNC surfaces, within the sub-oxide interface shell and in the SiO2 matrix were evaluated. Atom probe tomography (APT) and its statistical evaluation provide detailed spatial P distributions. For the first time, we obtain ionisation states of P atoms in the SiNC/SiO2 system at room temperature using X-ray absorption near edge structure (XANES) spectroscopy, eliminating structural artefacts due to sputtering as occurring in XPS. K energies of P in SiO2 and SiNC/SiO2 superlattices (SLs) were calibrated with non-degenerate P-doped Si wafers. results confirm measured core level energies, connecting and explaining XANES spectra with h-DFT electronic structures. While P can diffuse into SiNCs and predominantly resides on interstitial sites, its ionization probability is extremely low, rendering P unsuitable for introducing electrons into SiNCs embedded in SiO2. Increased sample conductivity and photoluminescence (PL) quenching previously assigned to ionized P donors originate from deep defect levels due to P.

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“…2b ) which cover SiNCs with a thickness of 1 to 1.5 mono layers (MLs) 28 . This finding is supported by PL quenching reported for high P concentrations mentioned above 3 29 .…”

Section: Resultssupporting

confidence: 84%

Section: Discussionmentioning

confidence: 57%

Location and Electronic Nature of Phosphorus in the Si Nanocrystal − SiO2 System

König

Gutsch

Gnaser

et al. 2015

Sci Rep

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“…where P PbN (k) denotes the probability to have k defects on a Si NC and n PbN is the average number (expected value) of the P bN defects per NC. 59 Since only defect-free NCs can efficiently emit PL, the probability to have no defect (k ¼ 0) on a NC is directly related to the PL intensity I PL…”

Section: B the Role Of Non-radiative Defectsmentioning

confidence: 99%

Absence of quantum confinement effects in the photoluminescence of Si3N4–embedded Si nanocrystals

Hiller¹,

Zelenina²,

Gutsch³

et al. 2014

Journal of Applied Physics

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Superlattices of Si-rich silicon nitride and Si 3 N 4 are prepared by plasma-enhanced chemical vapor deposition and, subsequently, annealed at 1150 C to form size-controlled Si nanocrystals (Si NCs) embedded in amorphous Si 3 N 4 . Despite well defined structural properties, photoluminescence spectroscopy (PL) reveals inconsistencies with the typically applied model of quantum confined excitons in nitride-embedded Si NCs. Time-resolved PL measurements demonstrate 10 5 times faster time-constants than typical for the indirect band structure of Si NCs. Furthermore, a pure Si 3 N 4 reference sample exhibits a similar PL peak as the Si NC samples. The origin of this luminescence is discussed in detail on the basis of radiative defects and Si 3 N 4 band tail states in combination with optical absorption measurements. The apparent absence of PL from the Si NCs is explained conclusively using electron spin resonance data from the Si/Si 3 N 4 interface defect literature. In addition, the role of Si 3 N 4 valence band tail states as potential hole traps is discussed. Most strikingly, the PL peak blueshift with decreasing NC size, which is often observed in literature and typically attributed to quantum confinement (QC), is identified as optical artifact by transfer matrix method simulations of the PL spectra. Finally, criteria for a critical examination of a potential QC-related origin of the PL from Si 3 N 4 -embedded Si NCs are suggested. V C 2014 AIP Publishing LLC. [http://dx.

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“…Conversely, in the case of high concentrations or of well passivated (or undefective) samples, the impurities substitute to the host material atoms, by diffusing towards the most energetically favorable sites. 20 In the following we investigate the effect of n-type and p-type substitutional doping in the case of Si-NCs embedded in SiO 2 and of freestanding, colloidal Si-NCs. By means of ab initio total-energy calculations we identify the preferential location of dopants in the nanostructure, and its effect on the structural properties with respect to the undoped case.…”

Section: Introductionmentioning

confidence: 99%

Preferential Positioning of Dopants and Co-Dopants in Embedded and Freestanding Si Nanocrystals

Guerra

Ossicini

2014

J. Am. Chem. Soc.

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In this work we aim at understanding the effect of n- and p-type substitutional doping in the case of matrix-embedded and freestanding Si nanocrystals. By means of ab initio calculations we identify the preferential positioning of the dopants and its effect on the structural properties with respect to the undoped case. Subsequently, we consider the case of phosphorus and boron co-doped nanocrystals showing that, against the single-doping situation, the energetics strongly favors the binding of the impurities at the nanocrystal surface. Indeed we demonstrate that the polar B-P bond forms a stable permanent electric dipole that radially points inward in the nanocrystal. Such a noteworthy characteristic and its physical consequences are discussed alongside new potential applications.

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Doping efficiency of phosphorus doped silicon nanocrystals embedded in a SiO2 matrix

Abstract: A low thermal impact annealing process for SiO2-embedded Si nanocrystals with optimized interface quality

Cited by 38 publications

References 24 publications

Location and Electronic Nature of Phosphorus in the Si Nanocrystal − SiO2 System

Location and Electronic Nature of Phosphorus in the Si Nanocrystal − SiO2 System

Absence of quantum confinement effects in the photoluminescence of Si3N4–embedded Si nanocrystals

Preferential Positioning of Dopants and Co-Dopants in Embedded and Freestanding Si Nanocrystals

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