Electrical Performance and Bias-Stress Stability of Amorphous InGaZnO Thin-Film Transistors with Buried-Channel Layers

To improve the electrical performance and bias-stress stability of amorphous InGaZnO thin-film transistors (a-IGZO TFTs), we fabricated and characterized buried-channel devices with multiple-stacked channel layers, i.e., a nitrogen-doped a-IGZO film (front-channel layer), a conventional a-IGZO film (buried-channel layer), and a nitrogen-doped a-IGZO film (back-channel layer). The larger field-effect mobility (5.8 cm2V−1s−1), the smaller subthreshold swing value (0.8 V/dec, and the better stability (smaller threshold voltage shifts during bias-stress and light illumination tests) were obtained for the buried-channel device relative to the conventional a-IGZO TFT. The specially designed channel-layer structure resulted in multiple conduction channels and hence large field-effect mobility. The in situ nitrogen-doping caused reductions in both the front-channel interface trap density and the density of deep states in the bulk channel layers, leading to a small subthreshold swing value. The better stability properties may be related to both the reduced trap states by nitrogen-doping and the passivation effect of the nitrogen-doped a-IGZO films at the device back channels.

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Improving the electrical performance of solution processed oligothiophene thin-film transistors via structural similarity blending

Journal of Materials Chemistry C ◽

10.1039/c7tc00748e ◽

2017 ◽

Vol 5 (21) ◽

pp. 5048-5054 ◽

Cited By ~ 1

Author(s):

Tim Leydecker ◽

Laura Favaretto ◽

Duc Trong Duong ◽

Gabriella Zappalà ◽

Karl Börjesson ◽

...

Keyword(s):

Thin Film ◽

Thin Film Transistors ◽

Field Effect ◽

Structural Similarity ◽

Single Component ◽

Electrical Performance ◽

Field Effect Mobility ◽

Solution Processed

Here we show that the blending of structurally similar oligothiophene molecules is an effective approach to improve the field-effect mobility and Ion/Ioff as compared to single component based transistors.

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Numerical Analysis on Effective Mass and Traps Density Dependence of Electrical Characteristics of a-IGZO Thin-Film Transistors

Electronics ◽

10.3390/electronics9010119 ◽

2020 ◽

Vol 9 (1) ◽

pp. 119 ◽

Cited By ~ 3

Author(s):

Jihwan Park ◽

Do-Kyung Kim ◽

Jun-Ik Park ◽

In Man Kang ◽

Jaewon Jang ◽

...

Keyword(s):

Thin Film ◽

Effective Mass ◽

Thin Film Transistors ◽

Field Effect ◽

Electron Mass ◽

Simulation Methods ◽

Electrical Characteristics ◽

Field Effect Mobility ◽

Electron Effective Mass ◽

Amorphous Ingazno

We have investigated the effect of electron effective mass (me*) and tail acceptor-like edge traps density (NTA) on the electrical characteristics of amorphous-InGaZnO (a-IGZO) thin-film transistors (TFTs) through numerical simulation. To examine the credibility of our simulation, we found that by adjusting me* to 0.34 of the free electron mass (mo), we can preferentially derive the experimentally obtained electrical properties of conventional a-IGZO TFTs through our simulation. Our initial simulation considered the effect of me* on the electrical characteristics independent of NTA. We varied the me* value while not changing the other variables related to traps density not dependent on it. As me* was incremented to 0.44 mo, the field-effect mobility (µfe) and the on-state current (Ion) decreased due to the higher sub-gap scattering based on electron capture behavior. However, the threshold voltage (Vth) was not significantly changed due to fixed effective acceptor-like traps (NTA). In reality, since the magnitude of NTA was affected by the magnitude of me*, we controlled me* together with NTA value as a secondary simulation. As the magnitude of both me* and NTA increased, µfe and Ion deceased showing the same phenomena as the first simulation. The magnitude of Vth was higher when compared to the first simulation due to the lower conductivity in the channel. In this regard, our simulation methods showed that controlling me* and NTA simultaneously would be expected to predict and optimize the electrical characteristics of a-IGZO TFTs more precisely.

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Effects of Li doping on the negative bias stress stability of solution-processed ZnO thin film transistors

RSC Advances ◽

10.1039/c5ra11480b ◽

2015 ◽

Vol 5 (84) ◽

pp. 68392-68396 ◽

Cited By ~ 1

Author(s):

Bokyung Kim ◽

Si Yun Park ◽

Jieun Ko ◽

Young-Jae Kim ◽

Youn Sang Kim

Keyword(s):

Thin Film Transistors ◽

Field Effect ◽

Negative Bias ◽

Zno Thin Film ◽

Electrical Characteristics ◽

Field Effect Mobility ◽

Li Doping ◽

Bias Stress ◽

Stability Of Solution ◽

Doped Zno

To investigate the effect of Li dopant on the electrical characteristics under negative bias stress (NBS), we analysed ZnO and Li doped ZnO TFTs. The Li dopant enhanced the field effect mobility and sustained the variation in Von of the ZnO TFTs.

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Effect of high conductivity amorphous InGaZnO active layer on the field effect mobility improvement of thin film transistors

Journal of Applied Physics ◽

10.1063/1.4902856 ◽

2014 ◽

Vol 116 (21) ◽

pp. 214504 ◽

Cited By ~ 10

Author(s):

Thanh Thuy Trinh ◽

Kyungsoo Jang ◽

Vinh Ai Dao ◽

Junsin Yi

Keyword(s):

Thin Film ◽

Active Layer ◽

Thin Film Transistors ◽

Field Effect ◽

High Conductivity ◽

Field Effect Mobility ◽

Amorphous Ingazno

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Effects of Capping Layers with Different Metals on Electrical Performance and Stability of p-Channel SnO Thin-Film Transistors

Micromachines ◽

10.3390/mi11100917 ◽

2020 ◽

Vol 11 (10) ◽

pp. 917

Author(s):

Min-Gyu Shin ◽

Kang-Hwan Bae ◽

Hwan-Seok Jeong ◽

Dae-Hwan Kim ◽

Hyun-Seok Cha ◽

...

Keyword(s):

Thin Film ◽

Thin Film Transistors ◽

Electrical Performance ◽

Electrical Characteristics ◽

Field Effect Mobility ◽

Bias Stress ◽

Significant Difference ◽

Channel Potential ◽

Work Functions ◽

The Difference

In this study, the effects of capping layers with different metals on the electrical performance and stability of p-channel SnO thin-film transistors (TFTs) were examined. Ni- or Pt-capped SnO TFTs exhibit a higher field-effect mobility (μFE), a lower subthreshold swing (SS), a positively shifted threshold voltage (VTH), and an improved negative-gate-bias-stress (NGBS) stability, as compared to pristine TFTs. In contrast, Al-capped SnO TFTs exhibit a lower μFE, higher SS, negatively shifted VTH, and degraded NGBS stability, as compared to pristine TFTs. No significant difference was observed between the electrical performance of the Cr-capped SnO TFT and that of the pristine SnO TFT. The obtained results were primarily explained based on the change in the back-channel potential of the SnO TFT that was caused by the difference in work functions between the SnO and various metals. This study shows that capping layers with different metals can be practically employed to modulate the electrical characteristics of p-channel SnO TFTs.

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Amorphous Oxide Thin Film Transistors with Nitrogen-Doped Hetero-Structure Channel Layers

10.20944/preprints201709.0028.v1 ◽

2017 ◽

Author(s):

Haiting Xie ◽

Guochao Liu ◽

Lei Zhang ◽

Yan Zhou ◽

Chengyuan Dong

Keyword(s):

Thin Film ◽

Thin Film Transistors ◽

Oxide Semiconductor ◽

Oxide Thin Film ◽

Electrical Performance ◽

Large Field ◽

Stress Tests ◽

Amorphous Oxide ◽

Nitrogen Doped ◽

Bias Stress

The nitrogen-doped amorphous oxide semiconductor (AOS) thin film transistors (TFTs) with double-stacked channel layers (DSCL) were prepared and characterized. The DSCL structure composed of nitrogen-doped amorphous InGaZnO and InZnO films (a-IGZO:N/a-IZO:N or a-IZO:N/a-IGZO:N) made the corresponding TFT devices exhibit quite large field-effect mobility due to the existence of double conduction channels. Especially, the a-IZO:N/a-IGZO:N TFTs showed even better electrical performance (μFE = 15.0 cm2·V-1·s-1, SS = 0.5 V/dec, VTH = 1.5 V, ION/IOFF = 1.1×108) and stability (VTH shift of 1.5, -0.5, and -2.5 V for positive bias-stress, negative bias-stress and thermal stress tests, respectively) than the a-IGZO:N/a-IZO:N TFTs. Based on the X-ray photoemission spectroscopy measurements and energy band analysis, it was assumed that the optimized interface trap states, the less ambient gas adsorption, and the better suppression of oxygen vacancies in the a-IZO:N/a-IGZO:N hetero-structures might be responsible for the better behaviors of the corresponding TFTs.

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Importance of Blade-Coating Temperature for Diketopyrrolopyrrole-based Thin-Film Transistors

Crystals ◽

10.3390/cryst9070346 ◽

2019 ◽

Vol 9 (7) ◽

pp. 346 ◽

Cited By ~ 2

Author(s):

Jun-Ik Park ◽

Hyeon-Seok Jeong ◽

Do-Kyung Kim ◽

Jaewon Jang ◽

In Man Kang ◽

...

Keyword(s):

Thin Film ◽

Thin Film Transistors ◽

Field Effect ◽

Room Temperature ◽

Electrical Performance ◽

Electrical Characteristics ◽

Field Effect Mobility ◽

Donor Acceptor ◽

Coating Temperature ◽

Blade Coating

In this work, the effect of blade-coating temperature on the electrical properties of a conjugated donor–acceptor copolymer containing diketopyrrolopyrrole (DPP)-based thin-film transistors (TFTs) was systematically analyzed. The organic semiconductor (OSC) layers were blade-coated at various blade-coating temperatures from room temperature (RT) to 80 °C. No remarkable changes were observed in the thickness, surface morphology, and roughness of the OSC films as the blade-coating temperature increased. DPP-based TFTs exhibited two noticeable tendencies in the magnitude of field-effect mobility with increasing blade-coating temperatures. As the temperature increased up to 40 °C, the field-effect mobility increased to 148% compared to the RT values. On the contrary, when the temperature was raised to 80 °C, the field-effect mobility significantly reduced to 20.9% of the mobility at 40 °C. These phenomena can be explained by changes in the crystallinity of DPP-based films. Therefore, the appropriate setting of the blade-coating temperature is essential in obtaining superior electrical characteristics for TFTs. A blade-coating temperature of 40 °C was found to be the optimum condition in terms of electrical performance for DPP-based TFTs.

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Influence of Active Channel Layer Thickness on SnO2 Thin-Film Transistor Performance

Electronics ◽

10.3390/electronics10020200 ◽

2021 ◽

Vol 10 (2) ◽

pp. 200

Author(s):

Do Won Kim ◽

Hyeon Joong Kim ◽

Changmin Lee ◽

Kyoungdu Kim ◽

Jin-Hyuk Bae ◽

...

Keyword(s):

Thin Film ◽

Field Effect ◽

Thin Film Transistor ◽

Sol Gel ◽

Precursor Concentration ◽

Sno2 Thin Film ◽

Field Effect Mobility ◽

Si Substrates ◽

Channel Layer ◽

Active Channel

Sol-gel processed SnO2 thin-film transistors (TFTs) were fabricated on SiO2/p+ Si substrates. The SnO2 active channel layer was deposited by the sol-gel spin coating method. Precursor concentration influenced the film thickness and surface roughness. As the concentration of the precursor was increased, the deposited films were thicker and smoother. The device performance was influenced by the thickness and roughness of the SnO2 active channel layer. Decreased precursor concentration resulted in a fabricated device with lower field-effect mobility, larger subthreshold swing (SS), and increased threshold voltage (Vth), originating from the lower free carrier concentration and increase in trap sites. The fabricated SnO2 TFTs, with an optimized 0.030 M precursor, had a field-effect mobility of 9.38 cm2/Vs, an SS of 1.99, an Ion/Ioff value of ~4.0 × 107, and showed enhancement mode operation and positive Vth, equal to 9.83 V.

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