Local structure and conduction mechanism in amorphous In–Ga–Zn–O films

Cho, Deok‐Yong; Song, Jaewon; Na, Kwang Duk; Hwang, Cheol Seong; Jeong, Jae Hoon; Jeong, Jae Kyeong; Mo, Yeon‐Gon

doi:10.1063/1.3103323

Cited by 67 publications

(53 citation statements)

References 14 publications

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“…As for PCZP structure, it is known that oxygen vacancies exist in the ZnO thin film naturally. 10,16 When positive bias was applied on the Pt top electrode, the negatively charged oxygen ions would move to the CuO layer, so the oxygen vacancies in the ZnO film increase and form the filament path to activate the resistance switching to LRS, as shown in Fig. 4(a).…”

Section: Resultsmentioning

confidence: 99%

CuO/ZnO memristors via oxygen or metal migration controlled by electrodes

Huang

Shen

et al. 2016

AIP Advances

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We carry out a comparative study on resistive switching in CuO/ZnO bilayer films; both samples grown Pt and Ag electrodes show bipolar switching behaviors. The two kinds of current-voltage curves reveal the different resistive switching behaviors in Pt/CuO/ZnO/Pt and Ag/CuO/ZnO/Pt, respectively. We conjecture that the formation and rupture of conducting filaments are responsible for the switching effect. Filaments induced by migration of oxygen ions are responsible for resistive switching with the Pt electrode. In contrast, resistive switching with the Ag electrode is attributed to the migration of metal cations and the corresponding electrochemical metallization. It is also inferred that the characteristic nature of the conducting filaments influences many aspects of switching characteristics, including the switching voltages and cycling variations at room temperature.

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Section: Resultsmentioning

confidence: 99%

CuO/ZnO memristors via oxygen or metal migration controlled by electrodes

Huang

Shen

et al. 2016

AIP Advances

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“…As expected, structural disorder increases with the substitution level in ternary and quaternary AOSs; however, there is no clear understanding regarding the role played by the individual metal species in the formation of amorphous state and the AOSs properties. Most research has focused on quaternary oxides such as a-In-Ga-Zn-O or a-Zn-In-Sn-O given their technological appeal; [48,49,[51][52][53][54][55][56][57][62][63][64][65][66]68,69,73,74,76] only a few studies addressed the properties of ternary AOSs systematically. [67,85,86] Moreover, a comparison of the results available in the literature is likely to be inconclusive because the crystallization temperature depends strongly not only on the metal composition but also on growth conditions (such as oxygen partial pressure, postdeposition temperatures and times) as well as film thickness.…”

Section: Local Structure and Amorphization Efficiencymentioning

confidence: 99%

“…The research area of transparent conducting oxides (TCOs) dates back to 1907 when CdO was reported to combine both optical transparency in the visible range and good electrical of amorphous indium oxide appeared in 2009, [61] followed by models of electron transport in multi-cation AOSs, [62][63][64][65][66][67] DFT calculations of defect formation, [68][69][70][71][72][73][74][75] and statistical descriptions of amorphous network. [76][77][78] However, several key questions regarding the nanostructure and morphology, crystallization, carrier generation, and conductivity mechanisms in AOSs remain unanswered and require a unified theoretical framework capable of handling all these aspects in tandem.…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in Understanding the Structure and Properties of Amorphous Oxide Semiconductors

Medvedeva

Buchholz

Chang

2017

Adv Elect Materials

139

144

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conductivity. [1] Following the discovery of SnO 2 with a similar unique combination of properties, [2] several patents were filed in the 1940s to employ TCOs as antistatic coatings and transparent heaters-long before the discovery of the now well-known Sn-doped In 2 O 3 (ITO) and Al-doped ZnO, [3] widely employed as flat panel display electrodes in the past decades. Despite great technological demand for TCOs [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and extensive experimental efforts to improve the conductivity via impurity doping, [21,22] to tune the work function and carrier concentration via cation composition, [23][24][25][26][27][28] to achieve two-dimensional transport via heterointerfaces, [29] and to p-dope the oxides toward active layers of transparent electronics, [30][31][32] theoretical understanding of these fascinating materials has lagged behind significantly. The first electronic band structure of ITO was calculated in 2001; [33] the role of native defects in prototype TCOs was understood after 2002; [34][35][36][37] the properties of multi-cation TCOs were first considered in 2004 [37][38][39][40][41][42] followed by modeling of novel TCO hosts [43,44] and spin-dependent transport in transition-metal-doped TCOs; [45] the nature of the band gap in In 2 O 3 was clarified in 2008; [46] and a first highthroughput search for p-type TCOs was performed in 2013. [47] Complex oxides that consist of multiple post-transition metals, such as InGaZnO 4 , have recently become competitive with silicon as the active transistor layer to drive arrays of pixels in large area displays. [9,[13][14][15][16][17][18][19]24] As the billion-dollar display industry moves forward, the amorphous phase of the complex oxides is favored both for flexible and high-resolution display applications. [13][14][15][16][48][49][50][51][52][53][54][55][56][57][58][59] The unique properties of AOSs were first demonstrated in 1990, [60] and the research area has been growing exponentially since then. Unlike Si-based semiconductors, AOSs were shown to exhibit optical, electrical, thermal, and mechanical properties that are comparable or even superior to those possessed by their crystalline counterparts. [48][49][50][51][52][53][54][55][56][57][58] Table 1 summarizes the key physical properties of best-performing crystalline TCOs and AOSs; the differences (or the lack thereof) between the two will be discussed in detail in the respective sections below.

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“…Since the 1990s, the multi-cation TCOs which include metal ions beyond the traditionally employed Sn, Cd, In and Zn have emerged, for example, MgIn 2 O 4 [7], GaInO 3 [8] and the so-called 2-3-3 or 3-3-4 systems where the numbers correspond to divalent, trivalent and tetravalent cations [9]. Among them, layered compounds of the homologous series (In,Ga) 2 O 3 (ZnO) n , where n=integer, attract an increasing attention [10][11][12][13][14][15][16][17][18][19][20][21][22], originally, due to a possibility to enhance conductivity via spatial separation of the carrier donors (dopants) located in insulating layers and the conducting layers which transfer the carriers effectively, i.e., without charge scattering. However, the electrical conductivity and carrier mobility observed to-date in these complex materials, σ=100-400 S/cm and µ=10-20 cm 2 /V·s, respectively [10,12,15,[23][24][25] are considerably lower than those achieved in the single-cation TCOs, such as In 2 O 3 , SnO 2 or ZnO, with σ=10 3 -10 4 S/cm and µ=50-100 cm 2 /V·s.…”

Section: Introductionmentioning

confidence: 99%

Tuning the properties of complex transparent conducting oxides: Role of crystal symmetry, chemical composition, and carrier generation

2010

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The electronic properties of single-and multi-cation transparent conducting oxides (TCOs) are investigated using first-principles density functional approach. A detailed comparison of the electronic band structure of stoichiometric and oxygen deficient In2O3, α-and β-Ga2O3, rock salt and wurtzite ZnO, and layered InGaZnO4 reveals the role of the following factors which govern the transport and optical properties of these TCO materials: (i) the crystal symmetry of the oxides, including both the oxygen coordination and the long-range structural anisotropy; (ii) the electronic configuration of the cation(s), specifically, the type of orbital(s) -s, p or d -which form the conduction band; and (iii) the strength of the hybridization between the cation's states and the p-states of the neighboring oxygen atoms. The results not only explain the experimentally observed trends in the electrical conductivity in the single-cation TCO, but also demonstrate that multicomponent oxides may offer a way to overcome the electron localization bottleneck which limits the charge transport in widebandgap main-group metal oxides. Further, the advantages of aliovalent substitutional doping -an alternative route to generate carriers in a TCO host -are outlined based on the electronic band structure calculations of Sn, Ga, Ti and Zr-doped InGaZnO4. We show that the transition metal dopants offer a possibility to improve conductivity without compromising the optical transmittance.

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Local structure and conduction mechanism in amorphous In–Ga–Zn–O films

Cited by 67 publications

References 14 publications

CuO/ZnO memristors via oxygen or metal migration controlled by electrodes

CuO/ZnO memristors via oxygen or metal migration controlled by electrodes

Recent Advances in Understanding the Structure and Properties of Amorphous Oxide Semiconductors

Tuning the properties of complex transparent conducting oxides: Role of crystal symmetry, chemical composition, and carrier generation

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