Optical properties of non-stoichiometric SiO2 as a function of excess silicon content and thermal treatments

Calleja, W.; Falcony, C.; Torres, A.; Aceves, M.; Osorio, Raquel

doi:10.1016/0040-6090(95)06857-0

Cited by 27 publications

(17 citation statements)

References 8 publications

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“…Previous characterizations of these kinds of films have involved techniques such as Raman and IR spectroscopy and ellipsometry. 7 In particular, Raman measurements have been used to determine a certain degree of crystallization of the excess silicon clustered together after performing the postdeposition annealing6 at different temperatures on Si-rich Si02 with an excess of Si less than 13% a/o. This work was based on the fact that crystalline silicon shows a single strong line in the Raman spectrum at n525 cm' associated to scattering from the threefold degenerate, k = 0 optical phonon of Si, while amorphous Si shows no sharp lines for frequencies above 200 cm' but rather a broad asymmetric peak at 480 cm'.…”

Section: Infroductionmentioning

confidence: 99%

Characterization of Excess Si in Nonstoichiometric SiO2 Films by Optical and Surface Analysis Techniques

Falcony

Calleja

Aceves

et al. 1997

J. Electrochem. Soc.

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Optical and surface analysis techniques such as infrared spectroscopy, ellipsometry and Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) have been used to study the way in which excess Si is incorporated in nonstoichiometric Si02 films deposited by a low pressure chemical vapor deposition technique. It has been found that for this range of silicon content, the Si atoms in excess either cluster into a well-defined second phase embedded in a Si03 matrix, or form a SiO type of material depending on the postdeposition thermal treatments given to the film. The oxides are deposited at a substrate temperature in the range of 650 to 750°C using a mixture of N70 and SiH4 gases. The excess Si is introduced by reducing the nitrous oxide to silane gas ratio during the deposition (this ratio was in the range of 4 to 200). After deposition, a densification process consisting of a 1000°C anneal in a nitrogen ambient for 30 mm was given to some of the samples. The refractive index, as determined by ellipsometry, is sensitive to the excess of silicon in the films, although its behavior was similar for both annealed and as-deposited samples. The volume percent of excess silicon was estimated using spectroscopic ellipsometry for some samples. Infrared spectroscopy, on the other hand, shows a clear shift of the stretching vibration peak of Si-O-Si bonds toward lower wave numbers as the Si excess in the film is increased in the case of as-deposited films, while the annealed samples do not present this effect. Also, as-deposited samples show an absorption peak, at 890 cm', that could be associated with partially oxidized silicon. AES and XPS spectra show a distinct difference in the peaks associated to Si bonded to either oxygen or another silicon atom for both types of samples indicating that at least a considerable part of the excess Si in the as-deposited samples is in the form of SiO, while in the annealed samples it is mostly forming a second phase within a silicon dioxide matrix. InfroductionTwo-phase Si/Si07 materials with an atomic percent (a/o) content of silicon in the range of 50 to 100%, generically known as polycrystalline silicon (SIPOS), has been extensively studied because of its electronic passivation properties on planar devices.1-4 Considerably less optical and structural characterization has been performed for lower concentrations of excess silicon (nonstoichiometric oxide), even though the electrical characteristics of Si07 films are considerably modified when excess silicon is introduced into them!2 The proposed applications for this material range from nonvolatile memories to electric field enhancers at the interface with SiO,, layers depending on the amount of excess silicon present in the film.'3 In particular, off-stoichiometric oxides with about 6% atom Si in excess have been proposed as the charge-transferring layer into a floating gate of a nonvolatile memory because the substantial reduction in permanent charge trapping as well as the highly nonlinear I-V characteristi...

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Section: Infroductionmentioning

confidence: 99%

Characterization of Excess Si in Nonstoichiometric SiO2 Films by Optical and Surface Analysis Techniques

Falcony

Calleja

Aceves

et al. 1997

J. Electrochem. Soc.

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“…SRO films were fabricated with different values of R 0 (10, 20 and 30), where R 0 = [N 2 O]/[SiH 4 ] is the ratio of reactive gas flows used as a parameter to determine the excess of the silicon in SRO films [8,9]. Films were annealed at 1000 • C for 30 min in N 2 atmosphere (densified).…”

Section: Methodsmentioning

confidence: 99%

Optical and electrical properties of silicon rich oxide films for optical sensors

Luna-López

Aceves-Mijares

Malik

2006

Sensors and Actuators A: Physical

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“…Under this condition, the stoichiometric SiO 2 deposition was obtained. 14,15 By turning the valve on and off in the N 2 O gas feeding line, the reactive a͒ gases in the deposition chamber were controlled. As a result, the Si and SiO 2 layers were deposited alternately.…”

Section: Methodsmentioning

confidence: 99%

Structural and optical properties of Si∕SiO2 superlattices prepared by low pressure chemical vapor deposition

Aceves-Mijares

Quiroga

et al. 2006

Journal of Applied Physics

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Si/ SiO 2 superlattices ͑SLs͒ structures were prepared using a low-pressure chemical vapor deposition ͑LPCVD͒ method. The structural and optical properties of the SLs materials were characterized using atomic force microscopy ͑AFM͒, Fourier transformed infrared ͑FTIR͒ absorption, x-ray diffraction, and room-temperature photoluminescence ͑PL͒ measurements. The AFM results show that a periodically layered Si/ SiO 2 structure was successfully deposited with nanometer-sized Si dots embedded in the Si layers. The FTIR spectra show that the SiO 2 near the Si/ SiO 2 interface is more ordered than the amorphous SiO 2 in the center of the SiO 2 layers. The Si/ SiO 2 SLs films show a room-temperature PL in the visible-near infrared wavelength region. The PL intensity is significantly enhanced by a high-temperature annealing at 1100°C. The peak position and intensity of the main emission band in the PL spectra strongly depend on the Si layer thickness. A pronounced redshift with increasing Si layer thickness is observed. This emission peak position can be fitted by the theory of quantum confinement effect in Si dots. The emission from recombination through defect and interface states was also observed in the SLs films.

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Optical properties of non-stoichiometric SiO2 as a function of excess silicon content and thermal treatments

Cited by 27 publications

References 8 publications

Characterization of Excess Si in Nonstoichiometric SiO2 Films by Optical and Surface Analysis Techniques

Characterization of Excess Si in Nonstoichiometric SiO2 Films by Optical and Surface Analysis Techniques

Optical and electrical properties of silicon rich oxide films for optical sensors

Structural and optical properties of Si∕SiO2 superlattices prepared by low pressure chemical vapor deposition

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