High Performance of a‐IZTO TFT by Purification of the Semiconductor Oxide Precursor

Bukke, Ravindra Naik; Mude, Narendra Naik; Saha, Jewel Kumer; Jang, Jin

doi:10.1002/admi.201900277

Cited by 40 publications

(51 citation statements)

References 61 publications

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“…Transport properties are closely related to metal-oxygen bond (MO), oxygen vacancies (V o ), and hydroxyl groups (OH) in the film. [1,12] The O 1s peak intensity could be deconvoluted into three peaks using Gaussian-Lorenz fitting method. The binding energies of oxygen related defects are ≈531 to ≈532 eV.…”

Section: Wwwadvelectronicmatdementioning

confidence: 99%

Extremely Stable, High Performance Gd and Li Alloyed ZnO Thin Film Transistor by Spray Pyrolysis

Saha

Bukke

Jang

2020

Adv Elect Materials

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ZnO is a well-known oxide semiconductor because of its excellent electrical and optical properties due to its crystalline structure with high carrier mobility and tunable bandgap by alloying. [13,14] Although, ZnO TFT has high carrier density with crystalline structure, it has some limitations, such as instabilities. It is known that the instability of pristine ZnO is related to the grain boundary defects related to oxygen vacancy and Zn interstitial. [15] Most of pristine ZnO TFTs show negative turn-on voltage owing to its high carrier concentration, which limits the application of the TFTs to gate drivers of active-matrix organic light-emitting diode display. Metal doping in ZnO, such as In, Li, N, F, Al, Ga, Hf, La, Mg, Y, and Zr is proposed to improve the performance and/or stability. [16-23] Many ternary and quaternary metal oxide TFTs are reported to improve both stability and mobility, but the results are not promising. Adamopoulos et al. [24] reported high mobility of ZnO TFT (85 cm 2 V −1 s −1) by Li incorporation on spray pyrolyzed ZrO x gate insulator. The increase in mobility by Li incorporation is due to the increase in grain size, but due to high carrier concentration and defects in semiconductor and interface, the offstate currents are high (10 −8 A). Whereas, Park et al. [25] reported La doping in amorphous IZO TFT which reduces the oxygen deficiency and improves the stability but the mobility is low (≈4.2 cm 2 V −1 s −1). Xifeng et al. [26] reported electron mobility ≈1.94 cm 2 V −1 s −1 by Hf doping in amorphous IZO TFT, where Hf works as carrier suppressor and increases the on/off current ratio by lowering the off-currents. Tue et al. [27] reported the Zr doping in amorphous IZO TFT to control the oxygen vacancies due to its lower slandered electron potential to the off current. Jun et al. [28] reported the La doping in amorphous ZTO TFT to improve the subthreshold swing and on/off current ratio. The electronegativity, ionic radius, and dopant-oxygen bond dissociation energy are important to improve the performance and stability of oxide TFT. As the difference of electronegativity between dopants and oxygen rises, the metaloxygen bond energy increases. Besides, the low standard electrode potential (SEP) of metal ion can decrease the traps due to its binding tendency with oxygen. [29] Higher bond dissociation energy leads to the stronger metal-oxygen network and less oxygen vacancy, which helps to improve the stability of the TFTs. [30] A Gd has lower electronegativity (1.20) compare to Zn (1.65), lower SEP (−2.27 V) compare to Zn (−0.76 V) and higher bond dissociation The simultaneous doping effect of Gadolinium (Gd) and Lithium (Li) on zinc oxide (ZnO) thin-film transistor (TFT) by spray pyrolysis using a ZrO x gate insulator is reported. Li doping in ZnO increases mobility significantly, whereas the presence of Gd improves the stability of the device. The Gd ratio in ZnO is varied from 0% to 20% and the Li ratio from 0% to 10%. The optimized ZnO TFT with codoping of 5% Li and 10% Gd exhibits...

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Section: Wwwadvelectronicmatdementioning

confidence: 99%

Extremely Stable, High Performance Gd and Li Alloyed ZnO Thin Film Transistor by Spray Pyrolysis

Saha

Bukke

Jang

2020

Adv Elect Materials

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“…The Electrical properties of gallium (0–20%) doped IZTO TFTs are summarized in Table 1 . Among all, 10% Ga‐doped IZTO TFT shows the best electrical properties due to the less traps at the surface as well as at/near the interface . In Figure e–h, the output curves of Ga‐doped IZTO TFTs show the saturation current levels of 13, 20, 24, and 15 µA for 0%, 5%, 10%, and 20% of Ga, respectively.…”

Section: Resultsmentioning

confidence: 94%

“…The improvements in the µs at and SS are due to less density of traps at the IZTO/gate insulator interface. [6,17,21,22] In Figure 4e-h, the output curves of Ga-doped IZTO TFTs show the saturation current levels of 13, 20, 24, and 15 µA for 0%, 5%, 10%, and 20% of Ga, respectively. [6] Our results suggest that higher M-O bond concentration reduces the defect concentration.…”

Section: Resultsmentioning

confidence: 99%

“…[8][9][10] The inkjet printing, [11,12] spray coating, [13] and spin coating [3][4][5][6][7] are popular methods for the solution processed, oxide TFTs. The solution-processed oxide TFTs commonly use high-dielectric constant (k) dielectric gate insulators such as aluminum oxide (AlO x ), [5,14,15] hafnium oxide (HfO x ), [16] and zirconium oxide (ZrO x ) [17][18][19][20][21][22] for high performance. The solution-processed oxide TFTs commonly use high-dielectric constant (k) dielectric gate insulators such as aluminum oxide (AlO x ), [5,14,15] hafnium oxide (HfO x ), [16] and zirconium oxide (ZrO x ) [17][18][19][20][21][22] for high performance.…”

Section: Introductionmentioning

confidence: 99%

“…Amorphous indium–gallium–zinc oxide (a‐IGZO) is usually used as the active layer with SiO 2 gate insulator by vacuum process. The solution‐processed oxide TFTs commonly use high‐dielectric constant ( k ) dielectric gate insulators such as aluminum oxide (AlO x ), hafnium oxide (HfO x ), and zirconium oxide (ZrO x ) for high performance.…”

Section: Introductionmentioning

confidence: 99%

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Highly Stable, Solution‐Processed Ga‐Doped IZTO Thin Film Transistor by Ar/O₂ Plasma Treatment

Mude

Bukke

Saha

et al. 2019

Adv Elect Materials

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their high optical transparency and high mobility. The undoped InO x and ZnO have a crystalline structure with high carrier concentration. [23] Therefore, many attempts are carried out to improve TFT performance by using multi-component metal-oxides. [24][25][26][27][28][29][30][31][32] IGZO is a widely used metal-oxide because of its amorphous structure and relatively high mobility. [8,32] The mixing of two or more cations with different sizes and ionic charges is tried for amorphous phase with suppressing crystallization and carrier concentration. [24] The incorporation of an appropriate quantity of cations is required to form the substitutional doping and strong chemical bonding with oxygen ions for stable oxide TFTs. [25] The ionic radius and metal-oxygen bonding strength are the most critical parameters to improve the mobility and stability of metal oxide TFTs. To enhance the bias stability of oxide TFT, carrier suppressors such as Ga 3+ , Gd 3+ , La 3+ , Sc 3+ , and Y 3+ can be used. Ga can be a good choice due to its lower ionic radius (62 pm) and relatively strong bonding strength with oxygen (353.5 kJ mol −1 ). [33] The selection of an appropriate percentage of carrier suppressor is a vital parameter to control the carrier concentration. But, excess doping can modify the material structure, which leads to deteriorating device performance. Ga is used for IGZO, indium-gallium oxide (IGO), [26] and indium-gallium-zinc-tin oxide (IGZTO), [27] so that we selected Ga doping in IZTO to improve mobility and stability. The solution-processed alloyed form of the oxide TFTs fabricated using In-Ga-O, [26] indium-zinc oxide (In-Zn-O), [28] indiumzinc-tin oxide (In-Zn-Sn-O), [29] aluminum-doped indium zinc tin oxide (Al-In-Zn-Sn-O), [30] zinc tin oxide (Zn-Sn-O), [31] and indium gallium zinc oxide (In-Ga-Zn-O) [32] as an active channel material have been widely studied for the high performance of the solution based oxide TFTs. To increase mobility, various treatments were carried out such as heat-treatment [34] and plasma-treatment. [35][36][37] In this study, we report the Ar/O2 plasma treatment effect on the performance of Ga-doped IZTO TFT. First, we improve the performance of the a-IZTO TFT by varying the Ga doping ratio from 0 to 20%. It is found that 10% Ga-doped IZTO shows the best performance. To further improve the TFT performance, the Ar/O 2 plasma treatment was carried out. The carbon concentration at the surface of Ga-doped IZTO could be reduced by Ar/O 2 plasma treatment, which is confirmed from the XPS The effects of gallium doping into indium-zinc-tin oxide (IZTO) thin film transistors (TFTs) and Ar/O 2 plasma treatment on the performance of a-IZTO TFT are reported. The Ga doping ratio is varied from 0 to 20%, and it is found that 10% gallium doping in a-IZTO TFT results in a saturation mobility (µs at ) of 11.80 cm 2 V −1 s −1 , a threshold voltage (V th ) of 0.17 V, subthreshold swing (SS) of 94 mV dec −1 , and on/off current ratio (I on /I off ) of 1.21 × 10 7 . Additionally, the performance of 10% G...

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Wide Bandgap Oxide Semiconductors: from Materials Physics to Optoelectronic Devices

et al. 2021

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over 80% in the visible light range. [2] ITO is widely used as essential transparent conducting electrodes in flat panel displays, touch screens, and solar cells. The global ITO market has an annual growth rate of 15% and is valued at 7 billion USD in 2019. In 2004, Nomura and Hosono et al. made great breakthrough in oxide thin film transistor (TFT) based on amorphous indium gallium zinc oxide (IGZO) grown at room temperature. [3] The amorphous IGZO showed an impressive mobility of 9 cm 2 V −1 s −1 , about 10 times of amorphous hydrogenated Si TFT which was used exclusively for displays at that time. Soon after Hosono's seminal work, IGZO TFT was commercialized by Sharp Corporation in 2012, and then rapidly expanded to mobile phones, tablets and laptops. [4] In 2019, the fifth generation IGZO TFT went to mass production, capable of driving large-area displays (85 in.) with ultrahigh 8 K resolution. [5] Moreover, oxide TFTs are also considered as the most promising transistors for next-generation curved, flexible, or even rollable electronics. [6] The great success of oxide semiconductors is underpinned by their unique electronic structure, amenability for n-type doping, as well as intrinsic stability. Oxide semiconductors have bandgap larger than 3 eV, enabling transparency in the visible spectrum. The conduction band (CB) of oxide semiconductors is typically composed of empty ns-orbitals (n ≥ 4) of heavy posttransition metals. The large, spherical ns-orbitals give rise to a high electron mobility even in amorphous phases, as well as high dopability for hosting a high density of electrons. Therefore, oxide semiconductors are amendable via doping to be a transparent semiconductor or a transparent conductor, depending on the purposes of device applications, e.g., TFT or ITO. However, there are two sides to every coin. The nature of electronic structure of oxide semiconductors also leads to the fundamental limitation of achieving p-type oxide semiconductors, which is exacerbated by the presence of a high background electron density arising from the formation of unintentional defects and impurities. [1a,7] The lack of p-type semiconductor significantly limits the great potential of oxide electronics. [7b] A high electron density and defect states cause detrimental effects on oxide TFT device performance, such as a high off-current, lower mobility, and instability issues. [8] In the past two decades, considerable research efforts have been made to understand the microscopic origin of defect states and background electrons Wide bandgap oxide semiconductors constitute a unique class of materials that combine properties of electrical conductivity and optical transparency. They are being widely used as key materials in optoelectronic device applications, including flat-panel displays, solar cells, OLED, and emerging flexible and transparent electronics. In this article, an up-to-date review on both the fundamental understanding of materials physics of oxide semiconductors, and recent research progress on design of new...

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High Performance of a‐IZTO TFT by Purification of the Semiconductor Oxide Precursor

Cited by 40 publications

References 61 publications

Extremely Stable, High Performance Gd and Li Alloyed ZnO Thin Film Transistor by Spray Pyrolysis

Extremely Stable, High Performance Gd and Li Alloyed ZnO Thin Film Transistor by Spray Pyrolysis

Highly Stable, Solution‐Processed Ga‐Doped IZTO Thin Film Transistor by Ar/O₂ Plasma Treatment

Wide Bandgap Oxide Semiconductors: from Materials Physics to Optoelectronic Devices

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High Performance of a‐IZTO TFT by Purification of the Semiconductor Oxide Precursor

Cited by 40 publications

References 61 publications

Extremely Stable, High Performance Gd and Li Alloyed ZnO Thin Film Transistor by Spray Pyrolysis

Extremely Stable, High Performance Gd and Li Alloyed ZnO Thin Film Transistor by Spray Pyrolysis

Highly Stable, Solution‐Processed Ga‐Doped IZTO Thin Film Transistor by Ar/O2 Plasma Treatment

Wide Bandgap Oxide Semiconductors: from Materials Physics to Optoelectronic Devices

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Highly Stable, Solution‐Processed Ga‐Doped IZTO Thin Film Transistor by Ar/O₂ Plasma Treatment