Effects of Interfacial Passivation on the Electrical Performance, Stability, and Contact Properties of Solution Process Based ZnO Thin Film Transistors

Wan, Liaojun; He, Fuchao; Lin, Zhenhua; Su, Jie; Chang, Jingjing; Hao, Yue

doi:10.3390/ma11091761

Cited by 19 publications

(12 citation statements)

References 35 publications

(49 reference statements)

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“…Whereas, Fig. 4(d-f) www.nature.com/scientificreports www.nature.com/scientificreports/ and -OH groups are related to the improvement of the film quality [28][29][30][31][32][33][34][35] , The ZnO film without AA shows a higher percentage of the hydroxide group (12%) compared to the ZnO film with AA (6%). Oxygen vacancies are related to point defects in the crystalline ZnO film.…”

Section: Resultsmentioning

confidence: 97%

Significant improvement of spray pyrolyzed ZnO thin film by precursor optimization for high mobility thin film transistors

Saha

Bukke

Mude

et al. 2020

Sci Rep

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Metal-oxide thin-film transistors (TFT) fabricated by spray pyrolysis are of increasing interest because of its simple process and scalability. A bottleneck issue is to get a bubble-free and dense material. We studied the effect of ammonium acetate (AA) addition in the oxide precursor solution on the performance of spray-coated ZnO TFTs. AA acts as a stabilizer, which increases the solubility of the solution and enhances the film quality by reducing the defects. With AA addition in ZnO precursor, the films are coffee ring free with high mass density and better grain orientation. The ZnO TFT with AA exhibit a remarkable improvement of its device performance such as saturation mobility increasing from 5.12 to 41.53 cm 2 V −1 s −1 , the subthreshold swing decreasing from 340 to 162 mV/dec and on/ off current ratio increasing from ~10 5 to 10 8. Additionally, the TFTs show excellent stability with a low threshold voltage shift of 0.1 V under gate bias stress. Therefore, the addition of AA is a promising approach to achieve high-performance ZnO TFTs for low-cost manufacturing of displays.

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Section: Resultsmentioning

confidence: 97%

Significant improvement of spray pyrolyzed ZnO thin film by precursor optimization for high mobility thin film transistors

Saha

Bukke

Mude

et al. 2020

Sci Rep

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“…12.38 10 7 --2019 [23] e) LaInZnO/ b) SiN x 150 2.64 10 9 --2010 [44] a) LaInZnO/ b) SiN x 550 4.2 10 6 1 -2012 [45] a) HfInZnO/ b) SiN x 500 1.94 10 6 --2010 [26] a) ZrInZnO/ a) LaZrO 400 6.23 10 9 -3.5 2013 [27] a) LaZnSnO/ b SiO 2 500 4.2 10 8 --2016 [28] a) LaZnO/ b) ZrO x 350 22.43 10 8 ≈0 0.06 2020 [63] d) ZrZnO/ d) AlO x 150 12.38 10 7 -0.61 2019 [64] a) (ZnO/InO 3 )/ b) SiO 2 200 50 10 5 -3.4 2019 [65] a) ZnO/ b) SiO 2 150 4.5 10 6 22 2018 [66] e) YZnO/ b) SiO 2 150 9.8 10 7 -5.3 2019 [67] d) (ZnO/4MP)/ d) Al 2 O 3 150 30 10 5 -2.3 2020 [68] a)…”

Section: Resultsmentioning

confidence: 99%

“…The device performances such as mobility, on/off current ratio, and SS of previous reports with our results are summarized in Table 1. [1,23,24,[26][27][28]41,[44][45]52,[54][55][56][57][63][64][65][66][67][68] To explain the role of Gd and Li in ZnO, we propose a model shown in Figure 5d-f, where the Zn 2+ ion can be replaced by the Gd 3+ ion, reducing electron concentration in a channel. The Li + replaces the Zn 2+ interstitial site, inducing extra electron in the channel.…”

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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“…The interface state density N SS , as calculated from SS for unpassivated and passivated ZnO TFTs, are 2.69 × 10 12 and 7.38 × 10 11 cm −2 eV −1 , respectively. Table 1 shows the summary of device performances, such as μ FE , SS, and I ON /I OFF , including the data from the literatures [ 19 , 20 , 21 , 25 , 26 , 27 , 28 , 29 ].…”

Section: Resultsmentioning

confidence: 99%

Remarkable Stability Improvement of ZnO TFT with Al2O3 Gate Insulator by Yttrium Passivation with Spray Pyrolysis

et al. 2020

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We report the impact of yttrium oxide (YOx) passivation on the zinc oxide (ZnO) thin film transistor (TFT) based on Al2O3 gate insulator (GI). The YOx and ZnO films are both deposited by spray pyrolysis at 400 and 350 °C, respectively. The YOx passivated ZnO TFT exhibits high device performance of field effect mobility (μFE) of 35.36 cm2/Vs, threshold voltage (VTH) of 0.49 V and subthreshold swing (SS) of 128.4 mV/dec. The ZnO TFT also exhibits excellent device stabilities, such as negligible threshold voltage shift (∆VTH) of 0.15 V under positive bias temperature stress and zero hysteresis voltage (VH) of ~0 V. YOx protects the channel layer from moisture absorption. On the other hand, the unpassivated ZnO TFT with Al2O3 GI showed inferior bias stability with a high SS when compared to the passivated one. It is found by XPS that Y diffuses into the GI interface, which can reduce the interfacial defects and eliminate the hysteresis of the transfer curve. The improvement of the stability is mainly due to the diffusion of Y into ZnO as well as the ZnO/Al2O3 interface.

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Effects of Interfacial Passivation on the Electrical Performance, Stability, and Contact Properties of Solution Process Based ZnO Thin Film Transistors

Cited by 19 publications

References 35 publications

Significant improvement of spray pyrolyzed ZnO thin film by precursor optimization for high mobility thin film transistors

Significant improvement of spray pyrolyzed ZnO thin film by precursor optimization for high mobility thin film transistors

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

Remarkable Stability Improvement of ZnO TFT with Al2O3 Gate Insulator by Yttrium Passivation with Spray Pyrolysis

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