Instability of Amorphous Indium Gallium Zinc Oxide Thin Film Transistors under Light Illumination

Gosain, Dharam Pal; Tanaka, Tsutomu

doi:10.1143/jjap.48.03b018

Cited by 61 publications

(47 citation statements)

References 15 publications

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“…10 Thin-film transistors made of amorphous oxide semiconductors exhibit a variety of metastable changes in their transistor characteristics through carrier doping and optical [11][12][13] or electrical [14][15][16][17][18][19][20][21] (or both [21][22][23][24][25][26][27][28] ) excitation of carriers. Indium (In)-based amorphous oxide semiconductors are considered as a promising material for next-generation thin-film electronics and optoelectronics because they have high electron mobility, transparency, flexibility and uniformity.…”

Section: Introductionmentioning

confidence: 99%

Undercoordinated indium as an intrinsic electron-trap center in amorphous InGaZnO4

Nahm

Kim

2014

NPG Asia Mater

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Undercoordinated indium (In*) is found to be an intrinsic defect that acts as a strong electron trap in amorphous InGaZnO 4 . Conduction electrons couple with the under-coordinated In* via Coulomb attraction, which is the driving force for the formation of an In*-M (M = In, Ga, or Zn) bond. The new structure is stable in the electron-trapped (2-) charge state, and we designate it as an intrinsic (In*-M) 2 − center in amorphous InGaZnO 4 . The (In*-M) 2 − centers are preferentially formed in heavily n-doped samples, resulting in a doping limit. They are also formed by electrical/optical stresses, which generate excited electrons, resulting in a metastable change in their electrical properties. NPG Asia Materials (2014) 6, e143; doi:10.1038/am.2014.103; published online 14 November 2014 INTRODUCTIONThe identification of charge-trapping defects on the atomic scale has been achieved in crystalline semiconductors. A donor can capture carrier electrons with large lattice relaxations, forming a DX (donor (D) deactivated (X)) center, 1-5 whereas an acceptor traps holes, forming an AX (acceptor (A) deactivated (X)) center. [5][6][7] However, in amorphous semiconductors, even though many charge-trapping phenomena that can modify electronic device characteristics 8 and be applied to nonvolatile memory devices 9 have been observed, the atomic and electronic structures of the charge-trapping defects lack clear understanding.Amorphous oxide semiconductors seriously suffer from chargetrapping events. 10 Thin-film transistors made of amorphous oxide semiconductors exhibit a variety of metastable changes in their transistor characteristics through carrier doping and optical [11][12][13] or electrical [14][15][16][17][18][19][20][21] (or both [21][22][23][24][25][26][27][28] ) excitation of carriers. Indium (In)-based amorphous oxide semiconductors are considered as a promising material for next-generation thin-film electronics and optoelectronics because they have high electron mobility, transparency, flexibility and uniformity. [29][30][31][32][33] However, the success of these applications has been limited by the lack of stability in their electrical properties owing to charge trapping.Investigation of the charge-trapping defects on the atomic scale is an essential prerequisite to overcome the instability issue of the indiumbased amorphous oxide semiconductors. An oxygen-vacancy (V O ) defect has been suggested as a metastable hole-trap center. 34,35 Unlike in crystalline oxides, V O and M-interstitial (M i ) (M = In, Ga, or Zn) are essentially indistinguishable in amorphous oxides. An M-M bond configuration can be understood as a V O and as anSimilarly, an O-O bond configuration can be interpreted as an M-vacancy (V M ) and as an In this paper, we find that undercoordinated indium (In*) acts as an intrinsic electron-trap center in In-based amorphous oxide semiconductors. Conduction electrons are subjected to a strong conductionelectron-ion interaction near the undercoordinated In* and trapped there, forming an In*-M bond. ...

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Section: Introductionmentioning

confidence: 99%

Undercoordinated indium as an intrinsic electron-trap center in amorphous InGaZnO4

Nahm

Kim

2014

NPG Asia Mater

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“…Indeed, reports have indicated that visible illumination leads to electrical instability. For example, Takechi et al 6 and Gosain et al 7 both report a negative ⌬V T in In-Ga-Zn-O ͑IGZO͒ TFTs when illuminated with wavelength ͑͒ ϳ311 nm and Ͻ420 nm, respectively. The former attributed the negative ⌬V T in unpassivated devices to light-induced oxygen interstitials, while the latter ascribed it in passivated devices to hole trapping at light-created defects at interfaces.…”

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confidence: 99%

Persistent photoconductivity in Hf–In–Zn–O thin film transistors

Ghaffarzadeh

Nathan

Robertson

et al. 2010

Applied Physics Letters

153

119

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Passivated Hf–In–Zn–O (HIZO) thin film transistors suffer from a negative threshold voltage shift under visible light stress due to persistent photoconductivity (PPC). Ionization of oxygen vacancy sites is identified as the origin of the PPC following observations of its temperature- and wavelength-dependence. This is further corroborated by the photoluminescence spectrum of the HIZO. We also show that the gate voltage can control the decay of PPC in the dark, giving rise to a memory action.

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“…Such mechanisms do not exist in AOSs because of their ionic bonding [12]. However, the amorphous oxide TFTs do suffer from instabilities [9,[33][34][35][36]. We assume their surfaces are passivated, to avoid O 2 effects.…”

Section: Instabilitiesmentioning

confidence: 99%

“…A more important instability is under negative bias stress, under illumination [33][34][35][36]. Without illumination, there is little V T shift.…”

Section: Instabilitiesmentioning

confidence: 99%

Properties and doping limits of amorphous oxide semiconductors

Robertson

2012

Journal of Non-Crystalline Solids

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Instability of Amorphous Indium Gallium Zinc Oxide Thin Film Transistors under Light Illumination

Cited by 61 publications

References 15 publications

Undercoordinated indium as an intrinsic electron-trap center in amorphous InGaZnO4

Undercoordinated indium as an intrinsic electron-trap center in amorphous InGaZnO4

Persistent photoconductivity in Hf–In–Zn–O thin film transistors

Properties and doping limits of amorphous oxide semiconductors

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