Inherent paramagnetic defects in layered Si/SiO{sub 2} superstructures with Si nanocrystals

Journal Article · Sat Nov 15 04:00:00 UTC 2008 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2966690· OSTI ID:21185920

Jivanescu, M; Stesmans, A ^[1]; Zacharias, M ^[2]

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1. Department of Physics and INPAC-Institute for Nanoscale Physics and Chemistry, University of Leuven, Celestijnenlaan 200 D, B-3001 Leuven (Belgium)
2. IMTEK, Albert Ludwigs University Freiburg, Georges Koehler Alley 103, 79110 Freiburg (Germany)

An extensive electron spin resonance (ESR) analysis has been carried out on structures comprised of Si nanoparticles ({approx}2 nm across) embedded in a regular pattern in an amorphous SiO{sub 2} matrix, fabricated by the SiO/SiO{sub 2} superlattice approach, with the intent to reveal and quantify occurring paramagnetic defects. The as-grown state is found to exhibit only a Si dangling bond (DB) signal, which through combination of first and second harmonic X-, K-, and Q-band observations in combination with computer spectra simulation, could be conclusively disentangled as solely comprised of overlapping powder pattern spectra of P{sub b(0)} and P{sub b1} defects, the archetypal intrinsic defects of the Si/SiO{sub 2} interface, with no evidence for a D line (Si DBs in disordered Si). This indicates a full crystalline system of randomly oriented Si nanocrystals (NCs). The P{sub b(0)}/P{sub b1} defect system, pertaining to the NC-Si/SiO{sub 2} interfaces, is found to be both qualitatively and quantitatively much alike that of standard (high-quality) thermal Si/SiO{sub 2}. The system is inherent, remaining unaffected by subsequent UV/vacuum UV irradiations. Relying on the known properties of P{sub b}-type defects in standard microscopic Si/SiO{sub 2}, the data would comply with Si nanocrystallites, in average, predominantly bordered by (111) and (100) facets, perhaps with morphology, schematically, of [100] truncated (111) octahedrons. Based on independent NC particles counting, there appears a P{sub b}-type center at {approx}71% of the Si NCs indicating the latter to be comprised of two subsystems-with or without an incorporated strain relaxing interface defect-which in that case will exhibit drastically different defect-sensitive properties, such as, e.g., photoluminescence (PL). Upon additional optical irradiation, two more defects appear, i.e., the SiO{sub 2}-associated E{sub {gamma}}{sup '} and EX centers, where the observed density of the former, taken as criterion, indicates the SiO{sub 2} matrix to be of standard thermal oxide quality. Thus, the properties of the revealed crucial intrinsic point defects bear out a high quality of both the NC-Si/SiO{sub 2} interfaces and the embedding SiO{sub 2}, alike that of standard thermal Si/SiO{sub 2}. In combination with H passivation/depassivation treatments, the degrading impact of the optical excitation ({approx}360 nm) itself used during PL measurements has been studied, revealing weak ESR reactivation of P{sub b(0)}, P{sub b1}, and E{sub {gamma}}{sup '} defects.

• OSTI ID: 21185920
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 10 Vol. 104; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ELECTRON SPIN RESONANCE
HARMONIC GENERATION
IRRADIATION
MORPHOLOGY
NANOSTRUCTURES
PARAMAGNETISM
PARTICLES
PHOTOLUMINESCENCE
POINT DEFECTS
POWDERS
SIGNALS
SILICON
SILICON OXIDES
SIMULATION
SUPERLATTICES
ULTRAVIOLET RADIATION