skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Absence of quantum confinement effects in the photoluminescence of Si{sub 3}N{sub 4}–embedded Si nanocrystals

Abstract

Superlattices of Si-rich silicon nitride and Si{sub 3}N{sub 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{sub 3}N{sub 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{sup 5} times faster time-constants than typical for the indirect band structure of Si NCs. Furthermore, a pure Si{sub 3}N{sub 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{sub 3}N{sub 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{sub 3}N{sub 4} interface defect literature. In addition, the role of Si{sub 3}N{sub 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 themore » PL spectra. Finally, criteria for a critical examination of a potential QC-related origin of the PL from Si{sub 3}N{sub 4}-embedded Si NCs are suggested.« less

Authors:
; ; ;  [1];  [2];  [3]; ; ; ;  [4];  [4];  [5]; ; ; ;  [6]; ; ;  [7]
  1. Faculty of Engineering, IMTEK, Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg (Germany)
  2. Department of Electronic and Electrical Engineering, Trinity College Dublin, Dublin 2 (Ireland)
  3. (KTH), Electrum 229, Kista SE-16440 (Sweden)
  4. MIND-IN2UB, Departament d'Electrònica, Universitat de Barcelona, C. Martí i Franquès, 1, 08028 Barcelona (Spain)
  5. (Spain)
  6. Faculty of Mathematics and Physics, Department of Chemical Physics and Optics, Charles University in Prague, Ke Karlovu 3, CZ-12116 Prague 2 (Czech Republic)
  7. Fraunhofer-Institut für Solare Energiesysteme ISE, Heidenhofstr. 2, 79110 Freiburg (Germany)
Publication Date:
OSTI Identifier:
22304388
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 20; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; CHEMICAL VAPOR DEPOSITION; CRYSTALS; DEFECTS; ELECTRON SPIN RESONANCE; EXCITONS; INTERFACES; NANOMATERIALS; NANOSTRUCTURES; PHOTOLUMINESCENCE; PLASMA; SILICON; SILICON NITRIDES; SIMULATION; SPECTRA; SUPERLATTICES; TIME RESOLUTION; TRANSFER MATRIX METHOD; TRAPS

Citation Formats

Hiller, D., E-mail: daniel.hiller@imtek.uni-freiburg.de, Zelenina, A., Gutsch, S., Zacharias, M., Dyakov, S. A., Optics and Photonics, School of Information and Communication Technology, Royal Institute of Technology, López-Conesa, L., López-Vidrier, J., Peiró, F., Garrido, B., Estradé, S., CCiT, Scientific and Technical Centers, Universitat de Barcelona, C/Lluís Solé i Sabaris 1, 08028 Barcelona, Valenta, J., Kořínek, M., Trojánek, F., Malý, P., Schnabel, M., Weiss, C., and Janz, S. Absence of quantum confinement effects in the photoluminescence of Si{sub 3}N{sub 4}–embedded Si nanocrystals. United States: N. p., 2014. Web. doi:10.1063/1.4878699.
Hiller, D., E-mail: daniel.hiller@imtek.uni-freiburg.de, Zelenina, A., Gutsch, S., Zacharias, M., Dyakov, S. A., Optics and Photonics, School of Information and Communication Technology, Royal Institute of Technology, López-Conesa, L., López-Vidrier, J., Peiró, F., Garrido, B., Estradé, S., CCiT, Scientific and Technical Centers, Universitat de Barcelona, C/Lluís Solé i Sabaris 1, 08028 Barcelona, Valenta, J., Kořínek, M., Trojánek, F., Malý, P., Schnabel, M., Weiss, C., & Janz, S. Absence of quantum confinement effects in the photoluminescence of Si{sub 3}N{sub 4}–embedded Si nanocrystals. United States. doi:10.1063/1.4878699.
Hiller, D., E-mail: daniel.hiller@imtek.uni-freiburg.de, Zelenina, A., Gutsch, S., Zacharias, M., Dyakov, S. A., Optics and Photonics, School of Information and Communication Technology, Royal Institute of Technology, López-Conesa, L., López-Vidrier, J., Peiró, F., Garrido, B., Estradé, S., CCiT, Scientific and Technical Centers, Universitat de Barcelona, C/Lluís Solé i Sabaris 1, 08028 Barcelona, Valenta, J., Kořínek, M., Trojánek, F., Malý, P., Schnabel, M., Weiss, C., and Janz, S. 2014. "Absence of quantum confinement effects in the photoluminescence of Si{sub 3}N{sub 4}–embedded Si nanocrystals". United States. doi:10.1063/1.4878699.
@article{osti_22304388,
title = {Absence of quantum confinement effects in the photoluminescence of Si{sub 3}N{sub 4}–embedded Si nanocrystals},
author = {Hiller, D., E-mail: daniel.hiller@imtek.uni-freiburg.de and Zelenina, A. and Gutsch, S. and Zacharias, M. and Dyakov, S. A. and Optics and Photonics, School of Information and Communication Technology, Royal Institute of Technology and López-Conesa, L. and López-Vidrier, J. and Peiró, F. and Garrido, B. and Estradé, S. and CCiT, Scientific and Technical Centers, Universitat de Barcelona, C/Lluís Solé i Sabaris 1, 08028 Barcelona and Valenta, J. and Kořínek, M. and Trojánek, F. and Malý, P. and Schnabel, M. and Weiss, C. and Janz, S.},
abstractNote = {Superlattices of Si-rich silicon nitride and Si{sub 3}N{sub 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{sub 3}N{sub 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{sup 5} times faster time-constants than typical for the indirect band structure of Si NCs. Furthermore, a pure Si{sub 3}N{sub 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{sub 3}N{sub 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{sub 3}N{sub 4} interface defect literature. In addition, the role of Si{sub 3}N{sub 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{sub 3}N{sub 4}-embedded Si NCs are suggested.},
doi = {10.1063/1.4878699},
journal = {Journal of Applied Physics},
number = 20,
volume = 115,
place = {United States},
year = 2014,
month = 5
}
  • Through analysis of the latest experimental results reported in the literature and obtained in the laboratory, the authors have extended their previous quantum confinement/luminescence center model for the photoluminescence mechanism of porous Si and of nanometer-silicon-particle-embedded Si oxide films (G.G. Qin and Y.Q. Jia, Solid State Commun. 86, 559 (1993)). They consider that there are three main types of competitive photoexcitation/photoemission processes and that the process in which photoexcitation occurs in the nanometer silicon particles (NSPs) while photoemission occurs in the luminescence centers (LCs) in the SiO{sub x} layers very close to the NSPs is usually the major one. Theymore » discuss under what conditions the other two types of processes will dominate. They believe that the extended quantum confinement/luminescence center model is a physical model that is suitable for the photoluminescence from silicon oxide films embedded with NSPs or nanometer Ge particles (NGPs), as well as from oxidized porous Si.« less
  • The size dependent electronic absorption spectra of CdSe nanocrystals have been measured in a diamond anvil cell. Under pressure, these nanocrystals are reversibly converted from a direct gap wurtzite structure to a rock salt structure which has an indirect gap in the bulk. It is thus possible to compare the influence of quantum confinement on direct and indirect transitions in nanocrystals of the same size. The ratio of oscillator strength between direct and indirect structures does not change with size, indicating that zero-phonon transitions are not occurring in the indirect nanocrystals.
  • No abstract prepared.
  • Photoluminescence and X-ray photoelectron spectroscopy studies of Mn{sup 2+} doped ZnS nanocrystals in inorganic-organic hybrid coatings prepared by a sol-gel process are presented. A 25-fold enhancement of photoluminescence was observed after UV irradiation for 6 h in an ambient atmosphere. X-ray photoelectron spectroscopy results indicate a chemical shift of binding energy from ZnS to ZnSO{sub 4} after UV irradiation. X-ray diffraction results show a decrease of ZnS nanocrystal size during UV irradiation. The cause of these phenomena was discussed based on a photochemical reaction on ZnS nanocrystal surface.
  • Ge nanocrystals (NCs) embedded in silicon dioxide (SiO{sub 2}) matrix are grown by radio-frequency magnetron sputtering and studied in order to understand the origin of ultraviolet (UV) and blue photoluminescence (PL) from the NC-SiO{sub 2} system. Ge NCs of diameter 7-8 nm are formed after postdeposition annealing, as confirmed by transmission electron microscopy and Raman scattering studies. Optical Raman studies indicate the presence of strain in the embedded Ge NCs. Polarization dependent low frequency Raman studies reveal surface symmetrical and surface quadrupolar acoustic phonon modes of Ge NCs. PL studies with 488 nm excitation shows a broad emission band peakedmore » at {approx}545 nm, which is attributed to oxygen deficient defects in the SiO{sub 2} matrix. PL studies with 325 nm excitation show additional strong peaks in the 377-400 nm region. Time resolved PL studies in the UV-blue range show double exponential decay dynamics in the nanosecond time scale, irrespective of the NC size. Comparative studies of PL emission from SiO{sub 2} layers with no Ge content and with Ge content show that the {approx}400 nm PL emission is originated from a defective NC/SiO{sub 2} interface and the band is not unique to the presence of Ge. PL excitation spectroscopy measurements show large Stokes shift for the UV emission bands. We propose that the intense UV peaks at {approx}377 nm is originated from the twofold coordinated silicon defect at the interface between NC and SiO{sub 2} matrix and it is not necessarily specific to the presence of Ge in the oxide matrix. It is believed that due to the influence of strain on the NCs and interface states, PL from quantum confined carriers may be partially quenched for the embedded Ge NCs.« less