Effects of thermally induced anatase-to-rutile phase transition in MOCVD-grown TiO2 films on structural and optical properties

Won, Dongju; Wang, C.-H.; Jang, Hyunchul; Choi, Doo Jin

doi:10.1007/s003390100804

Cited by 177 publications

(63 citation statements)

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“…According to the TEM results, we observe the phase transformation of the TiO 2 thin film as the cycle number increases during the ALD process. Heterogeneous nucleation and growth of anatase TiO 2 took place from the surface of the Si [31]. The phase transformation of the TiO 2 films from amorphous to anatase might reduce the filed-effect passivation of TiO 2 film (discuss in Section 3.2) [26,32].…”

Section: Characterization Of Ald Tio 2 Thin Filmsmentioning

confidence: 99%

Atomic Layer Deposition TiO2 Films and TiO2/SiNx Stacks Applied for Silicon Solar Cells

et al. 2016

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Titanium oxide (TiO 2 ) films and TiO 2 /SiN x stacks have potential in surface passivation, anti-reflection coatings and carrier-selective contact layers for crystalline Si solar cells. A Si wafer, deposited with 8-nm-thick TiO 2 film by atomic layer deposition, has a surface recombination velocity as low as 14.93 cm/s at the injection level of 1.0 × 10 15 cm −3 . However, the performance of silicon surface passivation of the deposited TiO 2 film declines as its thickness increases, probably because of the stress effects, phase transformation, atomic hydrogen and thermal stability of amorphous TiO 2 films. For the characterization of 66-nm-thick TiO 2 film, the results of transmission electron microscopy show that the anatase TiO 2 crystallinity forms close to the surface of the Si. Secondary ion mass spectrometry shows the atomic hydrogen at the interface of TiO 2 and Si which serves for chemical passivation. The crystal size of anatase TiO 2 and the homogeneity of TiO 2 film can be deduced by the measurements of Raman spectroscopy and spectroscopic ellipsometry, respectively. For the passivating contacts of solar cells, in addition, a stack composed of 8-nm-thick TiO 2 film and a plasma-enhanced chemical-vapor-deposited 72-nm-thick SiN x layer has been investigated. From the results of the measurement of the reflectivity and effective carrier lifetime, TiO 2 /SiN x stacks on Si wafers perform with low reflectivity and some degree of surface passivation for the Si wafer.

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Section: Characterization Of Ald Tio 2 Thin Filmsmentioning

confidence: 99%

Atomic Layer Deposition TiO2 Films and TiO2/SiNx Stacks Applied for Silicon Solar Cells

et al. 2016

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“…9 Schematic illustration of the transformation of the film morphology larger than 14 nm (Zhang and Banfield, 1998;Hanaor and Sorrell, 2011). However, some investigations of the annealing effects on the transformation of TiO 2 films fabricated by sputter deposition (Wiggins et al, 1996), MOCVD (Won et al, 2001), and sol-gel dip-coating (Kim et al, 2002) reported that the transformation temperatures exceeded 600°C. Kumar et al (1993) investigated the difference in the transformation temperature between nanoparticle powder and nanoparticulate films both synthesized by the sol-gel method.…”

Section: Iii) Sintering Of Anatase Particles (700-900°c)mentioning

confidence: 99%

Effects of Annealing on the Morphology and Porosity of Porous TiO<sub>2</sub> Films Fabricated by Deposition of Aerosol Nanoparticles

Kubo

Mantani

2015

J. Chem. Eng. Japan / JCEJ

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The present study investigates the impact of post annealing of TiO 2 nanoparticulate lms on their crystallinity, mechanical strength, and morphology. Non-agglomerated and amorphous TiO 2 nanoparticles of 46 nm diameter were synthesized in a plasma eld, and were subsequently deposited on substrates to form nanoparticulate lms. The lms were annealed at various temperatures in the range of 100-1,200°C. Phase transformations from amorphous-to-anatase and from anatase-to-rutile were observed at 400°C and at 1,000°C, respectively. The high rutile transformation temperature was considered to be due to a tensile eld induced by shrinkage of the lm. The as-deposited lm and the lms annealed at below 400°C had poor mechanical strength. Conversely, the lms annealed at over 500°C were strengthened by necking of the nanoparticles. The size of nanoparticles changed with increasing temperature. Annealing at 100-300°C caused the nanoparticles to shrink to approximately 30 nm. The nanoparticle diameters changed only slightly when annealed at 400-600°C because the annealing time was insu cient for changes to manifest. Annealing at 700-900°C caused the nanoparticle diameter to increase to approximately 50 nm because of sintering and coalescence of the nanoparticles. The diameter of the nanoparticles annealed at over 1,000°C became approximately 200 nm because of densi cation during the anatase-to-rutile transformation. The porosities of the lms annealed at below 900°C were over 80%. However, the porosities of the lms annealed at over 1,000°C decreased signi cantly due to densi cation.

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“…Due to interference of light, an oscillating structure with maxima and minima is typical for thin films optical transmittance/reflectance spectra. Optical parameters of thin films can be extracted from optical spectra using several conventional methods [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Most precise information for a thin film may be obtained from transmittance spectra measurements at normal incidence of light [9], because these measurements do not depend on the properties of etalon mirrors and angle of incidence of light (as in case of reflectance measurements).…”

Section: Introductionmentioning

confidence: 99%

“…When the refractive index of the film is higher than the index of the substrate ( > S ) the film transmittance is lower than the uncoated substrate transmittance [16]. In envelope methods [1][2][3][4][5][6][7][8][9] spectral extrema and their positions are applied for determination of (λ) and These methods are applicable for films of thickness in a limited range, for example > 0.2 µm for most oxide films [2]. For thinner films the number of extrema becomes insufficient and it is very difficult to locate them [2].…”

Section: Introductionmentioning

confidence: 99%

Determination of thin film refractive index and thickness by means of film phase thickness

Nenkov

Pencheva

2008

Open Physics

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Abstract:A new approach for determination of refractive index dispersion (λ) (the real part of the complex refractive index) and thickness of thin films of negligible absorption and weak dispersion is proposed. The calculation procedure is based on determination of the phase thickness of the film in the spectral region of measured transmittance data. All points of measured spectra are included in the calculations. Barium titanate thin films are investigated in the spectral region 0.38 -0.78 µm and their (λ) and are calculated. The approach is validated using Swanepoel's method and it is found to be applicable for relatively thin films when measured transmittance spectra have one minimum and one maximum only. PACS

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Effects of thermally induced anatase-to-rutile phase transition in MOCVD-grown TiO2 films on structural and optical properties

Cited by 177 publications

References 0 publications

Atomic Layer Deposition TiO2 Films and TiO2/SiNx Stacks Applied for Silicon Solar Cells

Atomic Layer Deposition TiO2 Films and TiO2/SiNx Stacks Applied for Silicon Solar Cells

Effects of Annealing on the Morphology and Porosity of Porous TiO<sub>2</sub> Films Fabricated by Deposition of Aerosol Nanoparticles

Determination of thin film refractive index and thickness by means of film phase thickness

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