Effects of Annealing Atmosphere on Electrical Performance and Stability of High-Mobility Indium-Gallium-Tin Oxide Thin-Film Transistors

In this study, we examined the effects of the annealing atmosphere on the electrical performance and stability of high-mobility indium-gallium-tin oxide (IGTO) thin-film transistors (TFTs). The annealing process was performed at a temperature of 180 °C under N2, O2, or air atmosphere after the deposition of IGTO thin films by direct current magnetron sputtering. The field-effect mobility (μFE) of the N2- and O2-annealed IGTO TFTs was 26.6 cm2/V·s and 25.0 cm2/V·s, respectively; these values were higher than that of the air-annealed IGTO TFT (μFE = 23.5 cm2/V·s). Furthermore, the stability of the N2- and O2-annealed IGTO TFTs under the application of a positive bias stress (PBS) was greater than that of the air-annealed device. However, the N2-annealed IGTO TFT exhibited a larger threshold voltage shift under negative bias illumination stress (NBIS) compared with the O2- and air-annealed IGTO TFTs. The obtained results indicate that O2 gas is the most suitable environment for the heat treatment of IGTO TFTs to maximize their electrical properties and stability. The low electrical stability of the air-annealed IGTO TFT under PBS and the N2-annealed IGTO TFT under NBIS are primarily attributed to the high density of hydroxyl groups and oxygen vacancies in the channel layers, respectively.

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Electrical Performance and Stability Improvements of High-Mobility Indium–Gallium–Tin Oxide Thin-Film Transistors Using an Oxidized Aluminum Capping Layer of Optimal Thickness

Electronics ◽

10.3390/electronics9122196 ◽

2020 ◽

Vol 9 (12) ◽

pp. 2196

Author(s):

Hyun-Seok Cha ◽

Hwan-Seok Jeong ◽

Seong-Hyun Hwang ◽

Dong-Ho Lee ◽

Hyuck-In Kwon

Keyword(s):

Thin Film ◽

Tin Oxide ◽

Thin Film Transistors ◽

High Mobility ◽

Oxide Thin Film ◽

Electrical Performance ◽

Oxygen Species ◽

Optimal Thickness ◽

Capping Layer ◽

Indium Gallium

We examined the effects of aluminum (Al) capping layer thickness on the electrical performance and stability of high-mobility indium–gallium–tin oxide (IGTO) thin-film transistors (TFTs). The Al capping layers with thicknesses (tAls) of 3, 5, and 8 nm were deposited, respectively, on top of the IGTO thin film by electron beam evaporation, and the IGTO TFTs without and with Al capping layers were subjected to thermal annealing at 200 °C for 1 h in ambient air. Among the IGTO TFTs without and with Al capping layers, the TFT with a 3 nm thick Al capping layer exhibited excellent electrical performance (field-effect mobility: 26.4 cm2/V s, subthreshold swing: 0.20 V/dec, and threshold voltage: −1.7 V) and higher electrical stability under positive and negative bias illumination stresses than other TFTs. To elucidate the physical mechanism responsible for the observed phenomenon, we compared the O1s spectra of the IGTO thin films without and with Al capping layers using X-ray photoelectron spectroscopy analyses. From the characterization results, it was observed that the weakly bonded oxygen-related components decreased from 25.0 to 10.0%, whereas the oxygen-deficient portion was maintained at 24.4% after the formation of the 3 nm thick Al capping layer. In contrast, a significant increase in the oxygen-deficient portion was observed after the formation of the Al capping layers having tAl values greater than 3 nm. These results imply that the thicker Al capping layer has a stronger gathering power for the oxygen species, and that 3 nm is the optimum thickness of the Al capping layer, which can selectively remove the weakly bonded oxygen species acting as subgap tail states within the IGTO. The results of this study thus demonstrate that the formation of an Al capping layer with the optimal thickness is a practical and useful method to enhance the electrical performance and stability of high-mobility IGTO TFTs.

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Chemical Stability and Electrical Performance of Dual-Active-Layered Zinc–Tin–Oxide/Indium–Gallium–Zinc–Oxide Thin-Film Transistors Using a Solution Process

ACS Applied Materials & Interfaces ◽

10.1021/am400943z ◽

2013 ◽

Vol 5 (13) ◽

pp. 6108-6112 ◽

Cited By ~ 44

Author(s):

Chul Ho Kim ◽

You Seung Rim ◽

Hyun Jae Kim

Keyword(s):

Thin Film ◽

Tin Oxide ◽

Thin Film Transistors ◽

Solution Process ◽

Oxide Thin Film ◽

Electrical Performance ◽

Indium Gallium Zinc Oxide ◽

Zinc Oxide Thin Film ◽

Zinc Tin Oxide ◽

Indium Gallium

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Polycrystalline Indium Gallium Tin Oxide Thin-Film Transistors With High Mobility Exceeding 100 cm2/Vs

IEEE Electron Device Letters ◽

10.1109/led.2021.3055940 ◽

2021 ◽

Vol 42 (3) ◽

pp. 347-350

Author(s):

Bo Kyoung Kim ◽

Nuri On ◽

Cheol Hee Choi ◽

Min Jae Kim ◽

Shinhyuck Kang ◽

...

Keyword(s):

Thin Film ◽

Tin Oxide ◽

Thin Film Transistors ◽

High Mobility ◽

Oxide Thin Film ◽

Indium Gallium

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High-Mobility Inkjet-Printed Indium-Gallium-Zinc-Oxide Thin-Film Transistors Using Sr-Doped Al2O3 Gate Dielectric

Materials ◽

10.3390/ma12060852 ◽

2019 ◽

Vol 12 (6) ◽

pp. 852 ◽

Cited By ~ 6

Author(s):

Seungbeom Choi ◽

Kyung-Tae Kim ◽

Sung Park ◽

Yong-Hoon Kim

Keyword(s):

Thin Film ◽

Zinc Oxide ◽

Thin Film Transistors ◽

Gate Dielectric ◽

High Mobility ◽

Oxide Thin Film ◽

Indium Gallium Zinc Oxide ◽

Linear Type ◽

Channel Layer ◽

Indium Gallium

In this paper, we demonstrate high-mobility inkjet-printed indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) using a solution-processed Sr-doped Al2O3 (SAO) gate dielectric. Particularly, to enhance to the electrical properties of inkjet-printed IGZO TFTs, a linear-type printing pattern was adopted for printing the IGZO channel layer. Compared to dot array printing patterns (4 × 4 and 5 × 5 dot arrays), the linear-type pattern resulted in the formation of a relatively thin and uniform IGZO channel layer. Also, to improve the subthreshold characteristics and low-voltage operation of the device, a high-k and thin (~10 nm) SAO film was used as the gate dielectric layer. Compared to the devices with SiO2 gate dielectric, the inkjet-printed IGZO TFTs with SAO gate dielectric exhibited substantially high field-effect mobility (30.7 cm2/Vs). Moreover, the subthreshold slope and total trap density of states were also significantly reduced to 0.14 V/decade and 8.4 × 1011/cm2·eV, respectively.

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Effects of Double Active Layer and Acetic Acid Stabilizer on the Electrical Properties of a Solution-Processed Zinc Tin Oxide Thin-Film Transistor

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2015.11200 ◽

2015 ◽

Vol 15 (10) ◽

pp. 7743-7747 ◽

Cited By ~ 2

Author(s):

Ji Hun Shin ◽

Sang Jo Kim ◽

Seung Soo Ha ◽

Yong Jin Im ◽

Chan Hee Park ◽

...

Keyword(s):

Thin Film ◽

Acetic Acid ◽

Active Layer ◽

Tin Oxide ◽

Solution Process ◽

Oxide Thin Film ◽

Electrical Performance ◽

Hydroxyl Groups ◽

Zinc Tin Oxide

We investigated the effects of a double active layer (DAL) and acetic acid stabilizer on zinc tin oxide (ZTO) thin-film transistors (TFTs) fabricated using a solution process. The DAL was composed of two layers created by a ZTO solution doped with the same or different percentiles of an atomic Sn concentration (30 at.%, 60 at.%). The electrical performance of the ZTO TFTs significantly was improved after we added acetic acid (AA) instead of monoethanolamine (MEA). This was accomplished by applying a type 2 DAL (bottom layer: Sn 60 at.%, top layer: Sn 30 at.%, 60/30) instead of other types (30/30 or 60/60). It was demonstrated that AA plays a role in lowering the decomposition temperature, enhancing the metal-oxygen bridge, and decreasing hydroxyl groups in the film. In addition, the type 2 DAL structure (60/30) lowered the Ioff of the ZTO TFT and controlled the carrier concentration in the channel. The best performances were obtained at a Sn concentration of 60 at.% in the bottom ZTO layer and 30 at.% in the top ZTO layer, with AA added as a stabilizer. The ZTO TFT exhibited an on/off ratio of 1.1×109, a saturation mobility of 5.04 cm2/V·s, a subthreshold slope of 0.11 V/decade, and a threshold voltage of 1.6 V.

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Electrical Performance and Reliability Improvement of Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors with HfO2 Gate Dielectrics by CF4 Plasma Treatment

Materials ◽

10.3390/ma11050824 ◽

2018 ◽

Vol 11 (5) ◽

pp. 824 ◽

Cited By ~ 6

Author(s):

Ching-Lin Fan ◽

Fan-Ping Tseng ◽

Chiao-Yuan Tseng

Keyword(s):

Thin Film ◽

Zinc Oxide ◽

Thin Film Transistors ◽

Gate Dielectrics ◽

Oxide Thin Film ◽

Electrical Performance ◽

Indium Gallium Zinc Oxide ◽

Zinc Oxide Thin Film ◽

Reliability Improvement ◽

Indium Gallium

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Impact of the Cation Composition on the Electrical Performance of Solution-Processed Zinc Tin Oxide Thin-Film Transistors

ACS Applied Materials & Interfaces ◽

10.1021/am503351e ◽

2014 ◽

Vol 6 (16) ◽

pp. 14026-14036 ◽

Cited By ~ 26

Author(s):

Yoon Jang Kim ◽

Seungha Oh ◽

Bong Seob Yang ◽

Sang Jin Han ◽

Hong Woo Lee ◽

...

Keyword(s):

Thin Film ◽

Tin Oxide ◽

Thin Film Transistors ◽

Oxide Thin Film ◽

Electrical Performance ◽

Cation Composition ◽

Solution Processed ◽

Zinc Tin Oxide

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Effects of Active Layer Thickness on the Electrical Characteristics and Stability of High-Mobility Amorphous Indium–Gallium–Tin Oxide Thin-Film Transistors

Electronics ◽

10.3390/electronics10111295 ◽

2021 ◽

Vol 10 (11) ◽

pp. 1295

Author(s):

Dae-Hwan Kim ◽

Hyun-Seok Cha ◽

Hwan-Seok Jeong ◽

Seong-Hyun Hwang ◽

Hyuck-In Kwon

Keyword(s):

Thin Film ◽

Thin Films ◽

Layer Thickness ◽

Active Layer ◽

Tin Oxide ◽

Thin Film Transistors ◽

High Mobility ◽

Active Layer Thickness ◽

Electrical Characteristics ◽

Indium Gallium

Herein, we investigated the effects of active layer thickness (tS) on the electrical characteristics and stability of high-mobility indium–gallium–tin oxide (IGTO) thin-film transistors (TFTs). IGTO TFTs, with tS values of 7 nm, 15 nm, 25 nm, 35 nm, and 50 nm, were prepared for this analysis. The drain current was only slightly modulated by the gate-to-source voltage, in the case of the IGTO TFT with tS = 50 nm. Under positive bias stress (PBS), the electrical stability of the IGTO TFTs with a tS less than 35 nm improved as the tS increased. However, the negative bias illumination stress (NBIS) stability of these IGTO TFTs deteriorated as the tS increased. To explain these phenomena, we compared the O1s spectra of IGTO thin films with different tS values, acquired using X-ray photoelectron spectroscopy. The characterization results revealed that the better PBS stability, and the low NBIS stability, of the IGTO TFTs with thicker active layers were mainly due to a decrease in the number of hydroxyl groups and an increase in the number of oxygen vacancies in the IGTO thin films with an increase in tS, respectively. Among the IGTO TFTs with different tS, the IGTO TFT with a 15-nm thick active layer exhibited the best electrical characteristics with a field-effect mobility (µFE) of 26.5 cm2/V·s, a subthreshold swing (SS) of 0.16 V/dec, and a threshold voltage (VTH) of 0.3 V. Moreover, the device exhibited robust stability under PBS (ΔVTH = 0.9 V) and NBIS (ΔVTH = −1.87 V).

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