Correlation between carrier concentration distribution, I-V and C-V characteristics of a-InGaZnO TFTs

Hsu, Chih-Chieh; Chen, Heping; Ting, Wei-Chieh

doi:10.1109/jdt.2015.2480871

Cited by 16 publications

(7 citation statements)

References 50 publications

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“…Thus, more free electrons were produced in the IGZO conduction band, which was the origin of the depletion mode of the TFT. 19 Additionally, depletion capacitance in IGZO would increase with the diffusion of Al atoms and increasing of carrier concentration near the source/drain regions, which was the origin of the large S.S. 25 In contrast, Ti is a reactive metal with a Pilling-Bedworth ratio at 1.5, and thus it tends to react with M-O bonds in IGZO, producing more oxygen vacancies (V O ) near the contact region, and a protective TiO x layer at the Ti/IGZO interface which can effectively prevent the endless redox reactions. 19 The lowest contact resistance was achieved for device A among the three devices without the deterioration of its switching speed and the alteration of the working mode.…”

Section: Resultsmentioning

confidence: 99%

Enhancement in Performance and Reliability of Transparent IGZO Thin-Film Transistors by ITO/Ti Stacked Source/Drain Contacts

Li,

Chen

2023

ECS J. Solid State Sci. Technol.

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Enhancement in performance and reliability of transparent IGZO thin-film transistors (TFTs) was achieved by adopting a laminated structure with a thin ITO layer and an ultrathin Ti layer as the source/drain (S/D) contacts. Compared with the transparent TFTs with pure ITO S/D contacts, a transparent TFT with the ITO/Ti S/D contacts showed a 300% enhancement in field-effect mobility from 4.75 to 12.10 cm2/Vs, 200% enhancement in on/off current ratio from 7.0×107 to 1.54×108, 300% reduction in contact resistance from 15.74 to 4.64 kΩ, and a decrease in threshold voltage from 3.11 to 2.80 V. The TFT with the ITO/Ti S/D contacts also maintained an extremely low leakage current at zero gate bias (for the device with channel width / channel length of 40 μm / 5 μm, the leakage current was ~ 1×10-13 A). In addition, the TFT with the ITO/Ti S/D contacts showed a hump-free transfer curve and a smaller shift in threshold voltage under negative bias illumination stress. The enhancement in performance and reliability makes the transparent TFT with the ITO/Ti S/D contacts very promising in transparent display applications.

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Section: Resultsmentioning

confidence: 99%

Enhancement in Performance and Reliability of Transparent IGZO Thin-Film Transistors by ITO/Ti Stacked Source/Drain Contacts

Li,

Chen

2023

ECS J. Solid State Sci. Technol.

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“…On the other hand, a charge model for AOS TFTs based on the same principles as the DC model explained above was developed [84]. A few previous papers [85,86,87] Charge expressions (gate, drain and source charges) are obtained for both the subthreshold and above-threshold current assuming that deep states dominate in the former regime and tail states in the latter.…”

Section: B Charge and Capacitance Modelmentioning

confidence: 99%

New Compact Modeling Solutions for Organic and Amorphous Oxide TFTs

Iñı́guez

Nathan

Kloes

et al. 2021

IEEE J. Electron Devices Soc.

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We review recent compact modeling solutions for Organic and Amorphous Oxide TFTs (OTFTs and AOS TFTs, respectively), which were developed, under the framework of the EU-funded project DOMINO, to address issues specifically connected to the physics of these devices. In particular, using different approaches, analytical equations were formulated to model the Density of States (DOS), different transport mechanisms, trapping/de-trapping, drain current, stress, capacitances, frequency dispersion and noise. The final TFT models were, after implementation in Verilog-A, validated by means of the design and simulation of test circuits.

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“…The transport in the disordered materials such asa-IGZO is dominated by various defects states in the band gap region. Thus the density of states model was employed to incorporate these defect states and the simulation of the generation, and arecombination process through traps in the forbidden gap was done using theShockley-Read-Hall model [27]. The following equations represent the density of different defect states ( ) g E including the acceptor-like band tail states, the donor-like band tail states, and the oxygen vacancy donor states, respectively.…”

Section: Device Simulationmentioning

confidence: 99%

Role of deposition and annealing of the top gate dielectric in a-IGZO TFT-based dual-gate ion-sensitive field-effect transistors

Kumar

Sutradhar

Kumar

et al. 2017

Semicond. Sci. Technol.

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The deposition of the top gate dielectric in thin film transistor (TFT)-based dual-gate ionsensitive field-effect transistors (DG ISFETs) is critical, and expected not to affect the bottom gate TFT characteristics, while providing a higher pH sensitive surface and efficient capacitive coupling between the gates. Amorphous Ta 2 O 5 , in addition to having good sensing properties, possesses a high dielectric constant of ∼25 making it well suited as the top gate dielectric in a DG ISFET by providing higher capacitive coupling (ratio of C top /C bottom ) leading to higher amplification. To avoid damage of the a-IGZO channel reported to be caused by plasma exposure, deposition of Ta 2 O 5 by e-beam evaporation followed by annealing was investigated in this work to obtain sensitivity over the Nernst limit. The deteriorated bottom gate TFT characteristics, indicated by anincrease in the channel conductance, confirmed thatplasma exposure is not the sole contributor to the changes. Oxygen vacancies at the Ta 2 O 5 /a-IGZO interface, which emerged during processing, increased the channel conductivity, becamefilled by optimum annealing in oxygen at 400 °C for 1 h, which was confirmed by anx-ray photoelectron spectroscopydepth profiling analysis. The obtained pH sensitivity of the TFTbased DG ISFET was 402 mVpH −1 , which is about 6.8 times the Nernst limit (59 mVpH −1 ). The concept of capacitive coupling was also demonstrated by simulating an a-IGZO-based DG TFT structure. Here, the exposure of the top gate dielectric tothe electrolyte without applying any top gate bias led to changes in the measured threshold voltage of the bottom gate TFT, and this obviated the requirement of a reference electrode needed in conventional ISFETs and other reported DG ISFETs. These devices, with high sensitivities and requiring low volumes (∼2 μl) of analyte solution, could be potential candidates for utilization as chemical sensors and biosensors.

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Correlation between carrier concentration distribution, I-V and C-V characteristics of a-InGaZnO TFTs

Cited by 16 publications

References 50 publications

Enhancement in Performance and Reliability of Transparent IGZO Thin-Film Transistors by ITO/Ti Stacked Source/Drain Contacts

Enhancement in Performance and Reliability of Transparent IGZO Thin-Film Transistors by ITO/Ti Stacked Source/Drain Contacts

New Compact Modeling Solutions for Organic and Amorphous Oxide TFTs

Role of deposition and annealing of the top gate dielectric in a-IGZO TFT-based dual-gate ion-sensitive field-effect transistors

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