Ultrathin Titanium Dioxide Nanolayers by Atomic Layer Deposition for Surface Passivation of Crystalline Silicon

Gad, Karim M.; Vossing, Daniel; Richter, Armin; Rayner, Bruce; Reindl, Leonhard M.; Mohney, Suzanne E.; Käsemann, Martin

doi:10.1109/jphotov.2016.2545404

Cited by 49 publications

(28 citation statements)

References 22 publications

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“…Among them, ALD‐TiO x thin layers have been intensely investigated since it functions as a good passivation layer for c‐Si surface due to the low deposition damage to c‐Si surface and the ability to fabricate sub 5 nm thick films. Indeed, it is well known that the good passivation performance is provided by the ALD‐TiO x /c‐Si heterocontact after postannealing at about 300 °C . We reported that the origin of improved passivation by postannealing is effusion of hydrogen and hydrogenated molecules from H‐terminated c‐Si and subsequent formation of a silicon oxide (SiO x ) layer at the TiO x /c‐Si interface .…”

Section: Influence Of the Siox Interlayers Prepared By Different Chemmentioning

confidence: 99%

Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Mochizuki

Gotoh

Kurokawa

et al. 2018

Adv Materials Inter

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Section: Influence Of the Siox Interlayers Prepared By Different Chemmentioning

confidence: 99%

Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Mochizuki

Gotoh

Kurokawa

et al. 2018

Adv Materials Inter

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“…In recent years, the search continued to find novel dielectrics with multifunctional capabilities in order to further alleviate the surface recombination, enhance the efficiency, and reduce the cost of c‐Si solar cells. Titanium oxide (TiO x ) is one such emerging dielectric for c‐Si solar cells due to its excellent optical properties, remarkable carrier selectivity, and excellent surface passivation features . Liao et al and Gad et al have previously demonstrated that atomic layer deposited (ALD) TiO x is able to provide excellent surface passivation on c‐Si surfaces, in addition to its ideal optical properties (refractive index of ≈2.4 at a wavelength of 632.8 nm and a relatively low absorption in the visible wavelength range) to be used as an antireflection coating (ARC) for encapsulated silicon wafer solar cells.…”

Section: Introductionmentioning

confidence: 99%

Evidence for Chemicals Intermingling at Silicon/Titanium Oxide (TiO_x) Interface and Existence of Multiple Bonding States in Monolithic TiO_x

Dwivedi

Yeo

Tan

et al. 2018

Adv Funct Materials

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Metal oxides (MOs) are used in photovoltaics and microelectronics as surface passivating layers and gate dielectrics, respectively. The effectiveness of MOs predominantly depends on their structure and the nature of the semiconductor/MO (S/MO) interface. While some efforts are made to analyze interface behavior of a few MOs, greater fundamental understanding on the interface and structural behaviors of emerging MOs is yet to be established for enhanced scientific and technological developments. Here, the structure of atomic layer deposited titanium oxide (TiO x ) and the nature of the c-Si/ TiO x interface on the atomic-to nanoscale are probed. A new breed of mixed oxide (SiO x +TiO x ) interfacial layer with a thickness of ≈1.3 nm at the c-Si/ TiO x interface is discovered, and its thickness further increases to ≈1.5 nm after postdeposition annealing. It is observed that both as-deposited and annealed monolithic TiO x films comprise multiple bonding states at varying film thickness, with an oxygen-deficient TiO x layer located close to the mixed oxide/TiO x interface. The stoichiometry of this layer improves when reaching the middle and near surface regions of the TiO x layer, respectively. This work uncovers several critical structural and interface aspects of TiO x , and thus creates opportunities to control and design improved photovoltaic and electronic devices for future development.

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“…Thin TiO2 films in amorphous phase can provide better Si surface passivation in the mechanisms of field-effect passivation and chemical passivation. The degradation of the surface passivation quality with increasing the TiO2 thickness could be caused by stress effects and phase transformation, which has been reported and proved [26,27,32]. Phase transformation of TiO2 at the interface could change the band structure and the interface trap density to decrease the field-effect passivation.…”

Section: Silicon Surface Passivation Of Ald Tio2mentioning

confidence: 95%

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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Ultrathin Titanium Dioxide Nanolayers by Atomic Layer Deposition for Surface Passivation of Crystalline Silicon

Cited by 49 publications

References 22 publications

Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Evidence for Chemicals Intermingling at Silicon/Titanium Oxide (TiO_x) Interface and Existence of Multiple Bonding States in Monolithic TiO_x

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

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Ultrathin Titanium Dioxide Nanolayers by Atomic Layer Deposition for Surface Passivation of Crystalline Silicon

Cited by 49 publications

References 22 publications

Local Structure of High Performance TiOx Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Local Structure of High Performance TiOx Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Evidence for Chemicals Intermingling at Silicon/Titanium Oxide (TiOx) Interface and Existence of Multiple Bonding States in Monolithic TiOx

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

Contact Info

Product

Resources

About

Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Evidence for Chemicals Intermingling at Silicon/Titanium Oxide (TiO_x) Interface and Existence of Multiple Bonding States in Monolithic TiO_x