Transparent Conducting Al-Doped ZnO Thin Films   Prepared by Pulsed Laser Deposition

Suzuki, Akio; Matsushita, Teruo; Wada, Naoki; Sakamoto, Yoshiaki; Okuda, Masahiro

doi:10.1143/jjap.35.l56

Cited by 172 publications

(64 citation statements)

References 14 publications

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“…Furthermore, such a low electrical resistivity is much better than those of other BZO films prepared by the liquid source misted chemical vapor deposition (LSMCD), and RF magnetron sputtering [36,42], and those of Al-doped ZnO thin films by spray pyrolysis, sol-gel spin coating methods, and facing targets sputtering [51,35,52]. Moreover, the electrical resistivity is comparable to those of the Al-doped ZnO thin films prepared by RF magnetron sputter, pulse laser deposition (PLD), and B, F-ZnO films prepared by the liquid source misted chemical vapor deposition (LSMCD) [53,54,37]. It is also noteworthy that the currently used electrospraying method is highly suitable for the preparation of B, F-ZnO films with low resistivity on the order of 10 À 4 at atmospheric conditions, which is comparable to the resistivity of films by pulsed laser deposition and the other above-mentioned methods.…”

Section: Electrical Characteristics Of Zno and B F-zno Thin Filmsmentioning

confidence: 95%

Conductivity enhancement by fluorine doping in boron-doped ZnO thin films deposited by the electrospraying method

Mahmood

Park

2012

Journal of Crystal Growth

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Section: Electrical Characteristics Of Zno and B F-zno Thin Filmsmentioning

confidence: 95%

Conductivity enhancement by fluorine doping in boron-doped ZnO thin films deposited by the electrospraying method

Mahmood

Park

2012

Journal of Crystal Growth

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“…The highest Q t values occur for DC or pulsed-DC plasma excitation; RF magnetron sputtering reduces Q t already by a factor of 2.5. The lowest trap densities are achieved by magnetron sputtering onto substrates mounted perpendicularly relative to the sputtering target (Minami et al [37], which reduces direct particle bombardment of the growing films), and for pulsed laser deposition [38,39].…”

Section: Amentioning

confidence: 99%

Carrier transport in polycrystalline transparent conductive oxides: A comparative study of zinc oxide and indium oxide

Ellmer

Mientus²

2008

Thin Solid Films

336

191

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Highly-doped indium-tin oxide films exhibit resistivities ρ as low as 1. . Thus the grain barrier trap densities of ZnO and ITO are significantly different, which seems to be connected with the defect chemistry of the two oxides and especially with the piezoelectricity of zinc oxide.Keywords Transparent conductive oxides, carrier transport, degenerate semiconductors, grain barriers, electron mobility 2 Therefore, in the present study the carrier transport processes in ITO and ZnO are compared in order to get a deeper understanding of the differences between these TCO materials. For this purpose conductivity and Hall mobility measurements on ZnO:Al and ITO films were undertaken for films deposited on amorphous as well as single crystalline substrates (sapphire) in order to determine the dominant scattering processes (ionized impurities, grain barriers, crystallographic defects). Our own data are compared with literature data reported for ZnO and ITO to show the general trends. Theoretical and semiempirical models are used to fit the experimental data and to derive characteristic material parameters for these three oxides. Introduction Theoretical modelsThe theoretical models on ionized impurity scattering were already reviewed in 2001 by one of the authors when estimating the mobility limit of highly-doped zinc oxide [3]. In the following a short summary is given to lay the basis for the further discussion.Ionized impurity scattering. This scattering process is caused by ionized dopant atoms and dominates for carrier concentrations above about 10 19 cm -3. An analytical expression for the mobility µ ii of degenerately doped semiconductors, taking into account the non-parabolicity of the conduction band, was given by Zawadzki [7] and refined by Pisarkiewicz et al. [6]:where the screening functionwith the parameter ξ np =1-m 0 */m*, which describes the non-parabolicity of the conduction band (m*, m 0 * -effective masses in the conduction band and at the conduction band edge, 4 respectively). The prefactor in equ. (1) The fit parameters µ max , µ min and µ min -µ 1 describe the lattice mobility at low carrier concentrations, the mobility limited by ionized impurity scattering and the clustering mobility, discussed above (see Table 2). . The ZnO mobility values were fitted using the empirical formula (3) and the fit parameters are summarized in Table 2 together with the corresponding values for silicon. In the transition region from lattice to ionized scattering for 5 . 10 16 < N < 5 . 10 18 cm -3 a large scattering of the experimental ZnO data can be observed. Therefore, the data have been fitted in analogy to the silicon data, which exhibit a much higher accuracy [14].However, the exact transition does not influence the conclusions much since we are interested predominantly in ionized impurity scattering in the region N > 10 19 cm -3 .5 Neutral impurity scattering. Neutral shallow-impurity scattering is often discussed in papers about transport in TCO films at room temperature [17,18]. The mobility due to ...

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“…High quality films have been repeatedly achieved by PLD, [33][34][35][36] with Agura and co-workers 33 having published a minimum resistivity of 85 ⍀ cm. These high values were mostly achieved by a very high carrier concentration, exceeding 10 21 cm −3 , while maximum mobilities were around 50 cm 2 / Vs. For sputtered films similar properties were achieved by Igasaki on sapphire substrates.…”

Section: Fig 4 ͑Color Online͒ Mobility Determined Hall Measurementsmentioning

confidence: 99%

Improved electrical transport in Al-doped zinc oxide by thermal treatment

Ruske

Roczen

Lee

et al. 2010

Journal of Applied Physics

176

100

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A postdeposition thermal treatment has been applied to sputtered Al-doped zinc oxide films and shown to strongly decrease the resistivity of the films. While high temperature annealing usually leads to deterioration of electrical transport properties, a silicon capping layer successfully prevented the degradation of carrier concentration during the annealing step. The effect of annealing time and temperature has been studied in detail. A mobility increase from values of around 40 cm2/Vs up to 67 cm2/Vs, resulting in a resistivity of 1.4×10−4 Ω cm has been obtained for annealing at temperatures of 650 °C. The high mobility increase is most likely obtained by reduced grain boundary scattering. Changes in carrier concentration in the films caused by the thermal treatment are the result of two competing processes. For short annealing procedures we observed an increase in carrier concentration that we attribute to hydrogen diffusing into the zinc oxide film from a silicon nitride barrier layer between the zinc oxide and the glass substrate and the silicon capping layer on top of the zinc oxide. Both are hydrogen-rich if deposited by plasma-enhanced chemical vapor deposition. For longer annealing times a decrease in carrier concentration can occur if a thin capping layer is used. This can be explained by the deteriorating effect of oxygen during thermal treatments which is well known from annealing of uncapped zinc oxide films. The reduction in carrier concentration can be prevented by the use of capping layers with thicknesses of 40 nm or more.

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Transparent Conducting Al-Doped ZnO Thin Films Prepared by Pulsed Laser Deposition

Cited by 172 publications

References 14 publications

Conductivity enhancement by fluorine doping in boron-doped ZnO thin films deposited by the electrospraying method

Conductivity enhancement by fluorine doping in boron-doped ZnO thin films deposited by the electrospraying method

Carrier transport in polycrystalline transparent conductive oxides: A comparative study of zinc oxide and indium oxide

Improved electrical transport in Al-doped zinc oxide by thermal treatment

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