Reduction of activation temperature at 150°C for IGZO films with improved electrical performance via UV-thermal treatment

Tak, Young Jun; Park, Sung Pyo; Jung, Tae Soo; Lee, Heesoo; Kim, Won Gi; Park, Jeong Woo; Kim, Hyun Jae

doi:10.1080/15980316.2016.1172524

Cited by 33 publications

(22 citation statements)

References 14 publications

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“…To solve this issue, AOSs are deposited under the oxygen-rich condition in order to reduce oxygen vacancy, but it inevitably accompanies a decrease in mobility. Thus, many studies regarding the reduction of V o without mobility deterioration, such as UV annealing 12 and high pressure oxygen annealing 13 , are reported. These methods can increase the metal oxide bond and decrease V o by chemical oxidation but it requires a prolonged time (1–2 hours) and additional external energy source.…”

Section: Introductionmentioning

confidence: 99%

The self-activated radical doping effects on the catalyzed surface of amorphous metal oxide films

Kim

Tak

Park

et al. 2017

Sci Rep

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In this study, we propose a self-activated radical doping (SRD) method on the catalyzed surface of amorphous oxide film that can improve both the electrical characteristics and the stability of amorphous oxide films through oxidizing oxygen vacancy using hydroxyl radical which is a strong oxidizer. This SRD method, which uses UV irradiation and thermal hydrogen peroxide solution treatment, effectively decreased the amount of oxygen vacancies and facilitated self-passivation and doping effect by radical reaction with photo-activated oxygen defects. As a result, the SRD-treated amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) showed superior electrical performances compared with non-treated a-IGZO TFTs. The mobility increased from 9.1 to 17.5 cm2/Vs, on-off ratio increased from 8.9 × 107 to 7.96 × 109, and the threshold voltage shift of negative bias-illumination stress for 3600 secs under 5700 lux of white LED and negative bias-temperature stress at 50 °C decreased from 9.6 V to 4.6 V and from 2.4 V to 0.4 V, respectively.

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Section: Introductionmentioning

confidence: 99%

The self-activated radical doping effects on the catalyzed surface of amorphous metal oxide films

Kim

Tak

Park

et al. 2017

Sci Rep

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“…Because it is difficult to apply Si-based TFTs to large high-resolution displays, many researchers have focused on modifying Si-based TFTs. Among the alternatives, there has been extensive research of oxide TFTs due to their high mobility, low off-current, high transparency, high uniformity, and simple deposition methods 3 4 5 6 7 8 9 . Some companies have already produced commercial products, including large AMOLED televisions, smart phones, and tablets.…”

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confidence: 99%

A solution-processed quaternary oxide system obtained at low-temperature using a vertical diffusion technique

Yoon

Kim

Tak

et al. 2017

Sci Rep

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We report a method for fabricating solution-processed quaternary In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) at low annealing temperatures using a vertical diffusion technique (VDT). The VDT is a deposition process for spin-coating binary and ternary oxide layers consecutively and annealing at once. With the VDT, uniform and dense quaternary oxide layers were fabricated at lower temperatures (280 °C). Compared to conventional IGZO and ternary In-Zn-O (IZO) thin films, VDT IGZO thin film had higher density of the metal-oxide bonds and lower density of the oxygen vacancies. The field-effect mobility of VDT IGZO TFT increased three times with an improved stability under positive bias stress than IZO TFT due to the reduction in oxygen vacancies. Therefore, the VDT process is a simple method that reduces the processing temperature without any additional treatment for quaternary oxide semiconductors with uniform layers.Silicon-based thin-film transistors (TFTs) have been used for backplanes since the birth of active-matrix liquid-crystal displays and active-matrix organic light-emitting diode (AMOLED) displays 1,2 . However, amorphous Si TFTs have poor electrical performance, and low-temperature polycrystalline Si TFTs have low scalability and high fabrication costs despite their enhanced electrical performance. Because it is difficult to apply Si-based TFTs to large high-resolution displays, many researchers have focused on modifying Si-based TFTs. Among the alternatives, there has been extensive research of oxide TFTs due to their high mobility, low off-current, high transparency, high uniformity, and simple deposition methods 3-9 . Some companies have already produced commercial products, including large AMOLED televisions, smart phones, and tablets.To maximize price competitiveness and enhance productivity, a solution process is necessary for oxide semiconductors 8,9 . However, solution-processed oxide TFTs have an inherent problem: poor electrical performance compared with vacuum-processed oxide TFTs. Higher processing temperatures are generally required to overcome this problem. However, at higher processing temperatures, it can be difficult to produce flexible devices because the maximum processing temperature of flexible substrates is below 300 °C. To resolve this issue, many researchers have focused on lowering the processing temperature while maintaining high electrical performance. There are three ways to lower the processing temperature: solution modulation, additional treatment, and structure modulation. For solution modulation, some research groups have tried different precursors 10,11 and solvents [12][13][14] . The processing temperature can be reduced by doping atoms 15 and various additives 16,17 introduced to oxide semiconductors. As additional treatments, high-pressure annealing (HPA) 18-20 , vacuum annealing 14,21,22 , ultraviolet (UV) annealing 21,23 , O 2 /O 3 annealing 24 , and microwave annealing 25,26 have been examined. Lastly, by changing or modulating the gate insulator materials 27-29...

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“…The Vth offset of all devices was found to be less than PBS, respectively. Since the a-IGZO TFT is an n-type semiconductor, and the n-type semiconductor has such a natural characteristic that the Vth shift of the oxide TFT under NBS is usually smaller than that of the PBS [16]. Therefore, the trapping of holes is lower than that of electron trapping only at a simple bias stress.…”

Section: Resultsmentioning

confidence: 99%

“…However, in actual production, stability and reliability are the key issues that IGZO TFT still exists and must be solved [6]- [8]. Several post-processing methods, such as thermal annealing [9], [10], plasma treatment [11], [12] and UV irradiation treatment [13]- [16], have been implemented in order to obtain a good IGZO TFT device. Among these posttreatment methods, thermal treatment typically requires temperatures above 300 • C to activate to achieve satisfactory semiconductor characteristics [10], and plasma treatment may destroy the surface of the active layer due to ion bombardment [12].…”

Section: Introductionmentioning

confidence: 99%

Improvement in Bias Stability of IGZO TFT With Etching Stop Structure by UV Irradiation Treatment of Active Layer Island

Pan

Yang

Chen

et al. 2020

IEEE J. Electron Devices Soc.

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In this paper, the effect of ultraviolet (UV) irradiation treatment of active layer IGZO on the bias stability of amorphous IGZO thin film transistor with etch stop (ES) structure is studied. Along with the increase in UV irradiation time, the surface of the IGZO film becomes smoother. An appropriate UV irradiation treatment cannot only improve the bias stress stability but also suppress the lump behavior generated by light illumination. The devices with irradiation time of 1 min exhibits an excellent properties with the field effect mobility of 15.07 cm 2 /V•s, subthreshold swing of 0.2 V/dec, and all bias stress less than 0.2 V including NIBS and PIBS. However, a relative long UV treatment would result in deteriorating the bias stability of devices. The fact implies that the reasonable UV irradiation treatment on the active layer island before depositing the ES layer is advantageous for improving the stability of the a-IGZO TFT device. INDEX TERMS a-IGZO thin film transistor, UV irradiation, stability.

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Reduction of activation temperature at 150°C for IGZO films with improved electrical performance via UV-thermal treatment

Cited by 33 publications

References 14 publications

The self-activated radical doping effects on the catalyzed surface of amorphous metal oxide films

The self-activated radical doping effects on the catalyzed surface of amorphous metal oxide films

A solution-processed quaternary oxide system obtained at low-temperature using a vertical diffusion technique

Improvement in Bias Stability of IGZO TFT With Etching Stop Structure by UV Irradiation Treatment of Active Layer Island

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