Photoconductivity of Ga doped polycrystalline ZnO films grown by reactive plasma deposition

Kishimoto, S.; Hayashi, Kei; Hamaguchi, Hirofumi; Makino, Hisashi; Yamada, Takahiro; Miyake, Aki; Yamamoto, Tetsuya

doi:10.1002/pssb.200675142

Cited by 5 publications

(4 citation statements)

References 11 publications

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“…This is consistent with our results that the values of drift mobility for electrons were larger than that of holes. However, the values obtained here seem to be somewhat small, compared with the values of Hall mobility [15]. When carriers are trapped and released by shallow levels, value of drift mobility becomes small, while value of Hall mobility does not.…”

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confidence: 57%

Drift mobility of photocarriers on Zn‐ and O‐polar surfaces of ZnO

Yamaguchi

Komiyama

Chonan

et al. 2010

Phys. Status Solidi (c)

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1 Introduction Zinc oxide (ZnO) is one of the most attractive materials for optoelectronic devices. This is due to its many advantages including a wide band gap energy of 3.4 eV, large exciton binding energy of 60 meV, low cost and low toxicity. The crystal structure of ZnO is wurtzite. ZnO has two polar surfaces along the c-axis, namely, the O-surface (000-1) and the Zn-surface (0001). This is because stacking sequences of atomic layers along the c-axis are asymmetric. Surface polarity effects on physical properties have been reported in the studies by photoluminescence [1], spectroscopic ellipsometry [2], scanning tunneling microscopy [3], X-ray diffraction and atomic force microscopy [4,5], transmission electron microscopy [6,7] and the Schottky diode characteristics [8]. As well, polarity controlled ZnO films have been successfully prepared by molecular-beam epitaxy [9][10][11]. Hence, it becomes more important to clarify the electric properties at polar surfaces for optoelectronic device application. In this paper, we have investigated the drift mobility of photocarriers generated at the two polar surfaces of ZnO by using the time of flight (TOF) technique.

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confidence: 57%

Drift mobility of photocarriers on Zn‐ and O‐polar surfaces of ZnO

Yamaguchi

Komiyama

Chonan

et al. 2010

Phys. Status Solidi (c)

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“…While synthesizing TCO thin films, it is a common practice to introduce impurities such as In, Al, Ga, N, P, As and F [5], within ZnO thin films in order to enhance the optoelectronic properties. ZnO : Ga (GZO) thin films have been deposited by several techniques such as molecular beam epitaxy [6], pulsed laser deposition [7], sintering [8], chemical spray [9,10], rf magnetron sputtering [11], ion plating [12] and solid state reaction [13]. Photoluminescence (PL) and 3 Author to whom any correspondence should be addressed.…”

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confidence: 99%

Gallium doping in transparent conductive ZnO thin films prepared by chemical spray pyrolysis

Babar

Deshamukh

Deokate

et al. 2008

J. Phys. D: Appl. Phys.

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Zinc oxide (ZnO) and ZnO : Ga films have been deposited by the spray pyrolysis method onto preheated glass substrates using zinc acetate and gallium nitrate as precursors for Zn and Ga ions, respectively. The effect of Ga doping on the structural, morphological, optical and electrical properties of sprayed ZnO thin films were investigated using x-ray diffraction (XRD), scanning electron microscopy , optical absorption, photoluminescence (PL) and Hall effect techniques. XRD studies reveal that films are polycrystalline with hexagonal (wurtzite) crystal structure. The thin films were oriented along the (0 0 2) plane. Room temperature PL measurements indicate that the deposited films exhibit proper doping of Ga in ZnO lattice. The average transparency in the visible range was around ∼85-95% for typical thin film deposited using 2 at% gallium doping. The optical band gap increased from 3.31 to 3.34 eV with Ga doping of 2 at%. The addition of gallium induces a decrease in electrical resistivity of the ZnO : Ga films up to 2 at% gallium doping. The highest figure of merit observed in this present study was 3.09 × 10 −3 cm 2 −1 .

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“…All these changes improved transparency in the visible range, indicating that some structural reformation had occurred. Kishimoto et al 13) also reported higher transmittance in the visible wavelength for films having higher carrier concentration. Another noticeable feature can be seen at shorter wavelengths where band-toband optical transition can be excited.…”

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confidence: 92%

Argon Plasma Treatment of Transparent Conductive ZnO Films

Akazawa

2009

Appl. Phys. Express

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The irradiation of undoped ZnO films with electron-cyclotron-resonance argon plasma was found to improve its transparent conductive properties. While both carrier concentration and Hall mobility increased with the irradiation time for all ZnO films, reduction in resistivity was more remarkable for films having higher resistivities. Optical transmittance in the visible wavelength continuously improved and the interference fringe for thick films was red shifted. These observations can consistently be explained by assuming that collision-induced desorption or low-energy sputtering by argon ions removed oxygen atoms within ZnO crystallites, which produced electron carriers and enlarged crystallites. #

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Photoconductivity of Ga doped polycrystalline ZnO films grown by reactive plasma deposition

Cited by 5 publications

References 11 publications

Drift mobility of photocarriers on Zn‐ and O‐polar surfaces of ZnO

Drift mobility of photocarriers on Zn‐ and O‐polar surfaces of ZnO

Gallium doping in transparent conductive ZnO thin films prepared by chemical spray pyrolysis

Argon Plasma Treatment of Transparent Conductive ZnO Films

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