• Transactions on Electrical and Electronic Materials
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• v.18 no.3
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• pp.141-143
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• 2017

Novel structured thin film transistors (TFTs) of amorphous silicon zinc tin oxide (a-SZTO) were designed and fabricated with a thin metal layer between the source and drain electrodes. A SZTO channel was annealed at $500^{\circ}C$. A Ti/Au electrode was used on the SZTO channel. Metals are deposited between the source and drain in this novel structured TFTs. The mobility of the was improved from $14.77cm^2/Vs$ to $35.59cm^2/Vs$ simply by adopting the novel structure without changing any other processing parameters, such as annealing condition, sputtering power or processing pressure. In addition, stability was improved under the positive bias thermal stress and negative bias thermal stress applied to the novel structured TFTs. Finally, this novel structured TFT was observed to be less affected by back-channel effect.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.9
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• pp.677-680
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• 2012

The dependency of annealing temperature on the electrical performances in amorphous silicon-zinc-tin-oxide thin film transistors (SZTO-TFT) has been investigated. The SZTO channel layers were prepared by using radio frequency (RF) magnetron sputtering method with different annealing treatment. The field effect mobility (${\mu}_{FE}$) increased and threshold voltage ($V_{th}$) shifted to negative direction with increasing annealing temperature. As a result, oxygen vacancies generated in SZTO channel layer with increasing annealing temperature resulted in negative shift in $V_{th}$ and increase in on-current.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.8
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• pp.580-583
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• 2012

The dependency of processing pressure on the electrical performances in amorphous silicon-zinc-tin-oxide thin film transistors (SZTO-TFT) has been investigated. The SZTO channel layers were deposited by using radio frequency (RF) magnetron sputtering method with different partial pressure. The field effect mobility (${\mu}_{FE}$) increased and threshold voltage ($V_{th}$) shifted to negative direction with increasing pressure during deposition processing. As a result, oxygen vacancies generated in SZTO channel layer with increasing partial pressure resulted in negative shift in $V_{th}$ and increase in on-current.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.5
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• pp.351-354
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• 2013

Thin-film transistors(TFTs) with silicon-zinc-tin-oxide(SiZnSnO, SZTO) channel layer are fabricated by rf sputtering method. Electrical properties were changed by different annealing treatment of dry annealing and wet annealing. This procedure improves electrical property especially, stability of oxide TFT. Improved electrical properties are ascribed to desorption of the negatively charged oxygen species from the surfaces by annealing treatment. The threshold voltage ($V_{th}$) shifted toward positive as increasing Si contents in SZTO system. Because the Si has a lower standard electrode potential (SEP) than that that of Sn, Zn, resulting in the degeneration of the oxygen vacancy ($V_O$). As a result, the Si acts as carrier suppressor and oxygen binder in the SZTO as well as a $V_{th}$ controller, resulting in the enhancement of stability of TFTs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.4
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• pp.272-275
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• 2019

We investigated the electrical characteristics of amorphous silicon-zinc-tin-oxide (a-SZTO) thin films deposited by RF-magnetron sputtering at room temperature depending on the deposition time. We fabricated a thin film transistor (TFT) with a bottom gate structure and various channel thicknesses. With increasing channel thickness, the threshold voltage shifted negatively from -0.44 V to -2.18 V, the on current ($I_{on}$) and field effect mobility (${\mu}_{FE}$) increased because of increasing carrier concentration. The a-SZTO film was fabricated and analyzed in terms of the contact resistance and channel resistance. In this study, the transmission line method (TLM) was adopted and investigated. With increasing channel thickness, the contact resistance and sheet resistance both decreased.

• Transactions on Electrical and Electronic Materials
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• v.16 no.1
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• pp.34-36
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• 2015

Amorphous SiZnSnO(SZTO) thin film transistors(TFTs) have been fabricated by RF magnetron sputtering process, and they were annealed in air and in wet ambient. The electrical performance and the structure were analyzed by I-V measurement, XPS, AFM, and XRD. The results showed improvement in device performance by wet annealing process compared to air annealing treatment, because free electron was shown to be increased due to reaction of oxygen and hydrogen generating oxygen vacancy. This is understood by the generation of free electrons. We expect the wet annealing process to be a promising candidate to contributing to high electrical performance of oxide thin film transistors for backplane device applications.

• Transactions on Electrical and Electronic Materials
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• v.17 no.1
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• pp.46-49
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• 2016

A thin film transistor (TFT) has been fabricated using the amorphous 0.5 wt% Si doped zinc-tin-oxide (a-0.5 SZTO) with different electrodes made of either aluminium (Al) or titanium/aluminium(Ti/Al). Contact resistance and total channel resistance of a-0.5SZTO TFTs have been investigated and compared using the transmission line method (TLM). We measured the total resistance of 1.0×10² Ω/cm using Ti/Al electrodes. This result is due to Ti, which is a material known for its adhesion layer. We found that the Ti/Al electrode showed better contact characteristics between the channel and electrodes compared with that made of Al only. The former showed a less contact and total resistance. We achieved high performance of the TFTs characteristic, such as Vth of 2.6 V, field effect mobility of 20.1 cm² V⁻¹s⁻¹, S.S of 0.9 Vdecade⁻¹, and on/off current ratio of 9.7×10⁶ A. It was demonstrated that the Ti/Al electrodes improved performance of TFTs due to enhanced contact resistance.