Modeling of amorphous InGaZnO4 thin film transistors and their subgap density of states

Hsieh, Hsing‐Hung; Kamiya, Toshio; Nomura, Kenji; Hosono, Hideo; Wu, Chung‐Chih

doi:10.1063/1.2857463

Cited by 333 publications

(224 citation statements)

References 16 publications

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“…11) On the other hand, Hall mobilities (® Hall ) and field-effect mobilities (® FE ) of a-IGZO TFTs with the chemical composition of In:Ga:Zn³1:1:1 in atomic ratio are reported to be 1015 cm 2 /Vs, 1),12) but some reports have provided much larger mobilities. Based on the device physics, ® FE should be smaller than drift mobility (³® Hall ) because ® FE include the deterioration effects by electron traps in the band gap and carrier scattering at the channelgate insulator interface; 13) actually, we have confirmed that ® FE of our a-IGZO TFTs are close to or a little bit smaller than ® Hall . 1), 13) In this work, we investigated the effects of an O 2 -and ozone-(O 3 -) annealing combined process on characteristics of a-IGZO TFTs, and observed a high saturation mobility (® sat ) of ³30 cm 2 / Vs.…”

Section: Introductionsupporting

confidence: 53%

“…Based on the device physics, ® FE should be smaller than drift mobility (³® Hall ) because ® FE include the deterioration effects by electron traps in the band gap and carrier scattering at the channelgate insulator interface; 13) actually, we have confirmed that ® FE of our a-IGZO TFTs are close to or a little bit smaller than ® Hall . 1), 13) In this work, we investigated the effects of an O 2 -and ozone-(O 3 -) annealing combined process on characteristics of a-IGZO TFTs, and observed a high saturation mobility (® sat ) of ³30 cm 2 / Vs. However, these TFTs showed large charging/discharging currents in the gate-to-source current (I GS ).…”

Section: Introductionsupporting

confidence: 53%

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Apparent high mobility ~30 cm<sup>2</sup>/Vs of amorphous In–Ga–Zn–O thin-film transistor and its origin

Xiao

Domen

Kamiya

et al. 2013

J. Ceram. Soc. Japan

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Amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) annealed in ozone at 250°C exhibited a good subthreshold swing (S) of 123 mV/decade and a saturation mobility (® sat ) of ³10 cm 2 /Vs, but a bit large threshold voltage (V th ) of 11.6 V. Further oxygen annealing at 200°C resulted in high apparent ® sat of ³30 cm 2 /Vs and deteriorated characteristics such as a large S value and large hysteresis. The high apparent ® sat values were attributed to the electrical discharge between the gate and source electrodes. Reasonably actual ® sat values ³10 cm 2 /Vs were obtained using the actual capacitance calculated from the discharge characteristics.

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Section: Introductionsupporting

confidence: 53%

Section: Introductionsupporting

confidence: 53%

Apparent high mobility ~30 cm<sup>2</sup>/Vs of amorphous In–Ga–Zn–O thin-film transistor and its origin

Xiao

Domen

Kamiya

et al. 2013

J. Ceram. Soc. Japan

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“…As seen in Figure 2(b), the S value for a-IGZO TFTs may be as low as 100 mV/decade. The subgap DOS has been examined by several methods, including device simulation [65] and the capacitance-voltage (C-V) method [66], as shown in Figure 7. Th e subgap states near the CBM in a-IGZO is more than one order of magnitude lower than that in a-Si:H, and a low subgap DOS is the reason why AOS TFTs exhibit small S values and operate at low voltages.…”

Section: Si 3pmentioning

confidence: 99%

Material characteristics and applications of transparent amorphous oxide semiconductors

2010

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A morphous semiconductors have created a new area of electronics known as 'giant microelectronics' typifi ed by devices such as solar cells and active-matrix (AM) fl at-panel displays. Single-crystalline semiconductor technology, typifi ed by crystal silicon electronics, is unsuitable for such applications, whereas amorphous or polycrystalline fi lms can be easily formed over large areas of greater than 1 m 2 at low temperature (e.g. < 400 °C) on both glass and plastic substrates, facilitating these new applications. Due to carrier scattering and trapping at defects on grain boundaries in polycrystalline materials (the grain boundary problem), hydrogenated amorphous silicon (a-Si:H) has been used more widely than polycrystalline silicon (p-Si) for practical large-size applications. However, the critical obstacles to be overcome to realize a-Si:H in future applications are low mobility (< 1 cm 2 /V s) and instability against electric stress and photo-illumination.In late 2004, we reported that an amorphous oxide semiconductor (AOS) with the composition a-InGaZnO 4 (a-IGZO) can be applied in the fabrication of fl exible, transparent thin-fi lm transistors (TFTs) having much improved performance compared to conventional TFTs based on a-Si:H and organic materials [1]. AOS materials have superior characteristics to conventional semiconductors, and therefore AOS TFT technology has grown very rapidly toward the realization of TFT backplanes for next-generation flat-panel displays. As summarized in Figure 1, a variety of prototype AM displays have been demonstrated by several companies within the last fi ve years since the fi rst report of AOS TFTs. Herein, we review the unique characteristics of AOS materials in relation to their TFT characteristics, and discuss why AOSs have such attractive electrical properties related to the electronic structures specifi c to transparent oxides. Active-matrix displays and circuits based on AOS TFT arraysTh e fi rst AOS-TFT was reported in late 2004 (see Figure 1). Just one year later, Toppan Printing quickly followed with the fi rst AM display based on AOS as a fl exible black-and-white electronic paper (e-paper) using a-IGZO TFTs

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“…Especially, it is well known that oxygen pressure during oxide film deposition influences the formation of subgap density of states which play an important role in the TFT performance. 7 However, there is still much unknown physics of the density of states in oxide-based TFTs such as its effect on the device characteristics and bias stability, the defect physics, and so on. We have reported that a ZnO deposited under a low oxygen partial pressure included lots of donor-like traps near the conduction energy and these traps deteriorated the subthreshold characteristics of ZnO TFTs.…”

mentioning

confidence: 99%

Effects of chemical stoichiometry of channel region on bias instability in ZnO thin-film transistors

Kamada

Fujita

Kimura

et al. 2011

Applied Physics Letters

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Demonstration and characterization of an ambipolar high mobility transistor in an undoped GaAs/AlGaAs quantum well Appl. Phys. Lett. 102, 082105 (2013) Investigation of the charge transport mechanism and subgap density of states in p-type Cu2O thin-film transistors Appl. Phys. Lett. 102, 082103 (2013) Negative gate-bias temperature stability of N-doped InGaZnO active-layer thin-film transistors Appl. Phys. Lett. 102, 083505 (2013) A pH sensor with a double-gate silicon nanowire field-effect transistor Appl. Phys. Lett. 102, 083701 (2013) Extrinsic and intrinsic photoresponse in monodisperse carbon nanotube thin film transistors Appl. Phys. Lett. 102, 083104 (2013) Additional information on Appl. Phys. Lett.

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Modeling of amorphous InGaZnO4 thin film transistors and their subgap density of states

Cited by 333 publications

References 16 publications

Apparent high mobility ~30 cm<sup>2</sup>/Vs of amorphous In–Ga–Zn–O thin-film transistor and its origin

Apparent high mobility ~30 cm<sup>2</sup>/Vs of amorphous In–Ga–Zn–O thin-film transistor and its origin

Material characteristics and applications of transparent amorphous oxide semiconductors

Effects of chemical stoichiometry of channel region on bias instability in ZnO thin-film transistors

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