Frequency-Dependent Complex Conductivities and Dielectric Responses of Indium Tin Oxide Thin Films From the Visible to the Far-Infrared

Chen, Ching-Wei; Lin, Yu‐Syuan; Chang, Chung-Yi; Yu, Peichen; Shieh, Jia-Min; Pan, Ci‐Ling

doi:10.1109/jqe.2010.2063696

Cited by 85 publications

(57 citation statements)

References 32 publications

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“…The large variation of the optical properties with film thickness can be an indication of the importance of the deposition conditions. For instance, Chen et al [8] used THz-TDS and Hall measurements to characterize ITO films of similar thickness, reporting dc conductivities in the range 1500-2200 Ω , significantly lower than our measurements, and a scattering time of 5.8-6.9 fs, comparable to our measurements on the 110-nm film, but significantly lower than our measurement (16.7 fs) on the 210-nm film. We have also performed FTIR measurements closing the gap between terahertz (0.5-18 THz) and ellipsometry (200-1000 THz) measurements.…”

Section: Drude and Drude-lorentz Fitsupporting

confidence: 70%

“…Many studies focus on impurity doped zinc oxides [4][5][6][7], like aluminum-or gallium doped zinc oxide (AZO and GZO), and tin-doped indium oxide (ITO) [8] due to their low loss and metallic behavior in the near infrared. With the emerging of terahertz time domain spectroscopy (THz-TDS), the frequency resolved conductive properties of a range of conductors, including thin gold films [9], highly doped silicon [10,11] and ITO [8] have been investigated between 0.2 and 2.7 THz. However, no broadband characterization of the complex conductivities of these TCO films has been performed in the THz range thus far.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ultrabroadband terahertz conductivity of highly doped ZnO and ITO

Wang¹,

Zalkovskij²,

Iwaszczuk³

et al. 2015

Opt. Mater. Express

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Abstract:The broadband complex conductivities of transparent conducting oxides (TCO), namely aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO) and tin-doped indium oxide (ITO), were investigated by terahertz time domain spectroscopy (THz-TDS) in the frequency range from 0.5 to 18 THz using air plasma techniques, supplemented by the photoconductive antenna (PCA) method. The complex conductivities were accurately calculated using a thin film extraction algorithm and analyzed in terms of the Drude conductivity model. All the measured TCOs have a scattering time below 15 fs. We find that a phonon response must be included in the description of the broadband properties of AZO and GZO for an accurate extraction of the scattering time in these materials, which is strongly influenced by the zinc oxide phonon resonance tail even in the low frequency part of the spectrum. The conductivity of AZO is found to be more thickness dependent than GZO and ITO, indicating high importance of the surface states for electron dynamics in AZO. Finally, we measure the transmittance of the TCO films from 10 to 200 THz with Fourier transform infrared spectroscopy (FTIR) measurements, thus closing the gap between THz-TDS measurements (0.5-18 THz) and ellipsometry measurements (200-1000 THz). ©2015 Optical Society of America

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Section: Drude and Drude-lorentz Fitsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Ultrabroadband terahertz conductivity of highly doped ZnO and ITO

Wang¹,

Zalkovskij²,

Iwaszczuk³

et al. 2015

Opt. Mater. Express

View full text Add to dashboard Cite

show abstract

“…7,8 However, related studies still face significant challenges: First, metal layers with a thickness of more than a few tens of nanometers are totally opaque, and the conductive indium tin oxide (ITO) films that are commonly used in the visible range also become highly reflective. 9 The lack of transparent electrodes makes the electric tuning of LCs difficult to achieve. Second, the dispersion of LC refractive indices induces a comparatively low birefringence in the THz regime.…”

Section: Introductionmentioning

confidence: 99%

Broadband tunable liquid crystal terahertz waveplates driven with porous graphene electrodes

et al. 2015

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Versatile devices, especially tunable ones, for terahertz imaging, sensing and high-speed communication, are in high demand. Liquid crystal based components are perfect candidates in the optical range; however, they encounter significant challenges in the terahertz band, particularly the lack of highly transparent electrodes and the drawbacks induced by a thick cell. Here, a strategy to overcome all these challenges is proposed: Few-layer porous graphene is employed as an electrode with a transmittance of more than 98%. A subwavelength metal wire grid is utilized as an integrated high-efficiency electrode and polarizer. The homogeneous alignment of a high-birefringence liquid crystal is implemented on both frail electrodes via a non-contact photo-alignment technique. A tunable terahertz waveplate is thus obtained. Its polarization evolution is directly demonstrated. Furthermore, quarter-wave plates that are electrically controllable over the entire testing range are achieved by stacking two cells. The proposed solution may pave a simple and bright road toward the development of various liquid crystal terahertz apparatuses.

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“…Many studies focus on aluminum-or gallium-doped zinc oxides [4][5][6][7] or tin-doped indium oxide 8,9 due to their low loss and metallic behavior in the near infrared. One more advantage of TCOs is the possibility of tuning their permittivity by design through deciding the dopants or the ratio of different components 10 , thus constituting an advantage over metals having fixed permittivity values.…”

Section: Introductionmentioning

confidence: 99%