Properties of TiO2-based transparent conducting oxide thin films on GaN(0001) surfaces

Kasai, Junpei; Hitosugi, Taro; Moriyama, Miki; Goshonoo, Koichi; Hoang, Ngoc Lam Huong; Nakao, Shin-ichi; Yamada, Naoomi; Hasegawa, Tetsuya

doi:10.1063/1.3326943

Cited by 44 publications

(37 citation statements)

References 16 publications

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“…Kasai et al [111] reported anatase Nb-doped TiO 2 TCO formation on GaN(0001) surfaces using a sputtering method. Thin films of Nb-doped TiO 2 were deposited on an insulating GaN(0001) template using RF sputtering at substrate temperatures (T s ) ranging from RT to 400°C.…”

Section: Sputteringmentioning

confidence: 98%

“…Transparent conducting TiO 2 films have been fabricated by various techniques [41][42][43][44][45][46]. These include both vacuumbased techniques (like sputtering, pulsed laser deposition-PLD, and chemical vapor deposition-CVD) and solutionbased techniques (like sol-gel, dip/spin-coating, and spray pyrolysis).…”

Section: Synthesis Of Tio 2 -Based Tsomentioning

confidence: 99%

“…The fabrication process should also have flexibility in tuning the TSO properties for improved device performance. ZnO, TiO 2 (Nb-doped TiO 2 -TNO), and doped SnO 2 are widely used as indium-free TSOs for low-e windows and other applications [17][18][19][20][21][22][23][41][42][43][44][45][46]. These materials are compared in Table 1.…”

Section: Introductionmentioning

confidence: 99%

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Recent developments in TiO2 as n- and p-type transparent semiconductors: synthesis, modification, properties, and energy-related applications

2015

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TiO 2 -based thin films and nanomaterials have been fabricated via physical and solution-based techniques by various research groups around the globe. Generally, most applications of TiO 2 involve photocatalytic activity for water and air purification, self-cleaning surfaces, antibacterial activity, and superhydrophilicity. As a widebandgap semiconductor, modified TiO 2 belongs to a class of materials called transparent semiconducting oxides (TSOs), which are simultaneously optically transparent and electrically conductive. TSOs continue to be in high demand for a variety of applications ranging from transparent electronics and sensor devices to light detecting and emitting devices in telecommunications. However, reports on TiO 2 applications as an effective TSO for transparent electronics applications have been limited. In general, TiO 2 is intrinsically an n-type semiconductor but can be doped to have p-type semiconductivity. This provides a very important opportunity to fabricate all-transparent homojunction devices for light harvesting and energy storage. P-type TSOs have recently attracted tremendous interest in the field of active devices for emerging transparent electronics for potential use in ultra-violet light-based solar cells. Therefore, a detailed overview of the synthesis, band structure modification via doping, properties, and applications of modified TiO 2 as n-and p-type TSOs is warranted. This article comprehensively reviews the latest developments. The discussion includes solution-based wet chemical techniques and vacuum-based dry physical techniques fabricating TiO 2 -TSOs. The synthesis of p-TiO 2 in particular is discussed in detail as it may provide interesting breakthroughs in emerging transparent electronics applications. Also, the structural, optical, and electrical properties of TiO 2 are discussed in the context of TSO applications, specifically the defect chemistry of TiO 2 to obtain n-and p-type semiconductivity, which could provide interesting insights into the band structure engineering of TiO 2 for conductivity reversal. Applications of both nand p-type TiO 2 have been reviewed in detail in relation to thin film transparent homo/heterojunction devices, dyesensitized solar cells, electrochromic displays, and other energy-related applications.

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Section: Sputteringmentioning

confidence: 98%

Section: Synthesis Of Tio 2 -Based Tsomentioning

confidence: 99%

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Recent developments in TiO2 as n- and p-type transparent semiconductors: synthesis, modification, properties, and energy-related applications

2015

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“…In general, the Sn doped In 2 O 3 (ITO) and F doped SnO 2 (FTO) are the most widely utilized n-type TCOs due to their excellent transparent conducting properties [5,6]. However, with the development of newly emerging optoelectronic devices, such as organic light emitting diodes (OLEDs), dye-sensitized solar cells (DSSCs), and GaN-based LEDs, it is still necessary to extend the material variety of TCOs [7] for the improvement of the performance of these devices [8].…”

Section: Introductionmentioning

confidence: 99%

First principles study on the p-type transparent conducting properties of rutile Ti1−xInxO2

Niu

Cheng

Huo

et al. 2012

Journal of Alloys and Compounds

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“…1,2 In addition to the existing TCO materials such as Sn-doped In 2 O 3 ͑ITO͒ and Al-doped ZnO ͑ZnO:Al͒, rare metal-free anatase-phase Nbdoped TiO 2 ͑A-TiO 2 :Nb͒ has attracted attention since Furubayashi et al 3 discovered its transparent conducting property. 7 To utilize the transparent conducting property of A-TiO 2 : Nb in general use, forming anatase films on glass and amorphous/noncrystalline substrates by a cost-effective and practical deposition technique is preferred. They first obtained ͑001͒ A-TiO 2 : Nb epitaxial films exhibiting low resistivity ͑͒ and high transmittance ͑T͒ comparable with ITO ͑Ref.…”

Section: Introductionmentioning

confidence: 99%

Transparent semiconducting Nb-doped anatase TiO2 films deposited by helicon-wave-excited-plasma sputtering

Fouda¹,

Hazu²,

Haemori³

et al. 2011

Journal of Vacuum Science & Technology B, Nanotechnology an

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Electrical and optical properties of Nb-doped TiO 2 films deposited by dc magnetron sputtering using slightly reduced Nb-doped TiO 2 − x ceramic targets J. Vac. Sci. Technol. A 28, 851 (2010); 10.1116/1.3358153 rf magnetron sputter deposition of transparent conducting Nb-doped Ti O 2 films on Sr Ti O 3 Transparent and semitransparent conducting film deposition by reactive-environment, hollow cathode sputtering A transparent metal: Nb-doped anatase Ti O 2The authors report stoichiometry control and postdeposition annealing-free fabrication of Nb-doped transparent anatase TiO 2 ͑A-TiO 2 :Nb͒ films on alkaline-free glass substrates by helicon-wave-excited-plasma sputtering. The films tended to crystallize in the stable electrically semi-insulating rutile phase. However, although the appropriate deposition condition window was narrow, precise stoichiometry control using near-reducing ambient, namely, the deposition temperature higher than 450°C and O 2 partial pressure ͑P O 2 ͒ in the range between 5 ϫ 10 −4 and 1 ϫ 10 −2 Pa, enabled the deposition of a high refractive index semiconducting anatase phase. The electron concentration of the A-TiO 2 : Nb films increased with increasing Nb concentration up to Ti 0.907 Nb 0.093 O 2 . The results indicate that the Nb 5+ donor on the Ti 4+ site can be activated under near-reducing atmosphere where unwanted compensating defects may be passivated. As a result, anatase Ti 0.907 Nb 0.093 O 2 film deposited at 500°C and P O 2 =5ϫ 10 −4 Pa exhibited a resistivity of 3.4ϫ 10 −3 ⍀ cm and an optical transmittance higher than 90%. The refractive index of A-TiO 2 :Nb was found to be approximately 2.63 at 450 nm with spectroscopic ellipsometry, which is comparable to the InGaN alloys.

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Properties of TiO2-based transparent conducting oxide thin films on GaN(0001) surfaces

Cited by 44 publications

References 16 publications

Recent developments in TiO2 as n- and p-type transparent semiconductors: synthesis, modification, properties, and energy-related applications

Recent developments in TiO2 as n- and p-type transparent semiconductors: synthesis, modification, properties, and energy-related applications

First principles study on the p-type transparent conducting properties of rutile Ti1−xInxO2

Transparent semiconducting Nb-doped anatase TiO2 films deposited by helicon-wave-excited-plasma sputtering

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