Analyzing the effects of ambient dependence for InGaZnO TFTs under illuminated bias stress

Chen, Te-Chih; Chang, Ting‐Chang; Hsieh, Tien-Yu; Tsai, Ming-Yen; Tsai, Chin-Hsien; Chen, Shih Ching; Lin, Chia-Sheng; Jian, Fu-Yen

doi:10.1016/j.surfcoat.2011.12.048

Cited by 9 publications

(8 citation statements)

References 21 publications

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“…O ) instead of electron trapping at the a-IGZO/ gate insulator (GI) interface [25]. We can see that the reaction rate is relatively large in the first few cycles and converges thereafter, which is also consistent with our previous work [23].…”

Section: The Response To Light Pulses With Different Duty Ratios a The Reaction Rate In Cycles Of Light Pulsessupporting

confidence: 91%

The Vacancy Pool Model for Amorphous In-Ga-Zn-O Thin-Film Transistors

Tai

Liu

Chan

2019

IEEE J. Electron Devices Soc.

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In this paper, the reaction rate of oxygen vacancy (V O ) by the derivatives of threshold voltage (Vth) in the amorphous indium-gallium-zinc oxide thin-film transistors under light pulses with altering duty ratios is investigated. More importantly, after collecting and analyzing a lot of experimental results, a comprehensive model named V O pool is proposed. The proposed model can more universally describe the characteristic of V O reacting to the light and its degradation behavior under various kinds of stress condition.INDEX TERMS Amorphous indium gallium zinc oxide (a-IGZO), thin-film transistors (TFTs), reaction rate, illumination effect, multiple-pulse illumination, response time, oxygen vacancy.

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Section: The Response To Light Pulses With Different Duty Ratios a The Reaction Rate In Cycles Of Light Pulsessupporting

confidence: 91%

The Vacancy Pool Model for Amorphous In-Ga-Zn-O Thin-Film Transistors

Tai

Liu

Chan

2019

IEEE J. Electron Devices Soc.

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“…[43][44][45][46][47][48][49][50][51][52][53][54][55]82 Single-crystalline IGZO (sc-IGZO) has a complex, layered structure with alternating stacks of InO 2 and GaO(ZnO) 2,7,10,27,28 as shown in Figure 1. 76 Unlike binary ZnO, a-IGZO can have a uniform amorphous phase because In 2 O 3 and Ga 2 O 3 promote glass phase formation, 29,[43][44][45][46][47][48][49][50][51][52][53][54][55]83 and the amorphous phase has been shown to be stable up to $500 C. 23 Many methods have been reported for a-IGZO deposition, including pulsed laser deposition (PLD), [23][24][25][26][27][28][29][30][31] but generally RF 20,25 or DC…”

Section: A Igzo Propertiesmentioning

confidence: 99%

“…[1][2][3][4][5][6] Several AOS materials have been studied including In-Zn-O, [7][8][9][10][20][21][22][23][24] In-Sn-O, 23,25 Zn-Sn-O, 23,25 Zn-In-Sn-O, 17,[23][24][25] and In-Ga-Zn-O (a-IGZO). [7][8][9][10][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] Among all AOS materials, a-IGZO has been the most widely investigated due to maintaining a very high electron mobility in the amorphous state (10-50 cm 2 V À1 s À1 ), and the wide controllability of carrier concentration through oxygen partial pressure during deposition. [8][9][10]…”

Section: Introductionmentioning

confidence: 99%

Energy band offsets of dielectrics on InGaZnO4

Hays

Gila

Pearton

et al. 2017

Applied Physics Reviews

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Thin-film transistors (TFTs) with channels made of hydrogenated amorphous silicon (a-Si:H) and polycrystalline silicon (poly-Si) are used extensively in the display industry. Amorphous silicon continues to dominate large-format display technology, but a-Si:H has a low electron mobility, l $ 1 cm 2 /V s. Transparent, conducting metal-oxide materials such as Indium-Gallium-Zinc Oxide (IGZO) have demonstrated electron mobilities of 10-50 cm 2 /V s and are candidates to replace a-Si:H for TFT backplane technologies. The device performance depends strongly on the type of band alignment of the gate dielectric with the semiconductor channel material and on the band offsets. The factors that determine the conduction and valence band offsets for a given material system are not well understood. Predictions based on various models have historically been unreliable and band offset values must be determined experimentally. This paper provides experimental band offset values for a number of gate dielectrics on IGZO for next generation TFTs. The relationship between band offset and interface quality, as demonstrated experimentally and by previously reported results, is also explained. The literature shows significant variations in reported band offsets and the reasons for these differences are evaluated. The biggest contributor to conduction band offsets is the variation in the bandgap of the dielectrics due to differences in measurement protocols and stoichiometry resulting from different deposition methods, chemistry, and contamination. We have investigated the influence of valence band offset values of strain, defects/vacancies, stoichiometry, chemical bonding, and contamination on IGZO/dielectric heterojunctions. These measurements provide data needed to further develop a predictive theory of band offsets. Published by AIP Publishing.

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“…• C) and high on/off ratio (∼10 6 ). 1 In addition, it is highly transparent in visible light with transmittance over 90% as illustrated due to wide bandgap (∼3 eV).…”

mentioning

confidence: 99%

The Time Response of the On-Current for the Amorphous In-Ga-Zn-O Thin Film Transistor to the Illumination Pulse

Tai¹,

Chang

Chen

et al. 2014

ECS J. Solid State Sci. Technol.

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In this study, the time response behavior of the amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs) to the illumination pulse is analyzed. The mechanism is proposed to correlate the oxygen vacancy reacting with the light-induced electron-hole pairs. The temperature effect on the time response to the illumination pulse is also studied. The higher excitation level, either from light or temperature, results in the similar excited and recovering behaviors. The formulas for the time response are proposed to be possibly used in the simulation for the circuit performance in real situation of illumination, which is important in the development of transparent electronics using a-IGZO TFT. Nowadays, amorphous-silicon (a-Si) thin film transistor (TFTs) have been used widely in flat-panel displays (FPD) in production, with the growing need for large area displays for home entertainment and the full adoption of digital broadcasting. Even with the success, there are still some drawbacks for the TFTs. For example, the low mobility leads to low open area in a pixel because of designing the large size to achieve the high current. For the state-of-art process rule with definite gate length, adopting TFTs with higher mobility is one possible solution to achieve high aperture ratio in a small pixel area without sacrificing the display performance. Therefore, new TFTs with high mobility are needed to replace a-Si TFTs. Among those newly proposed TFTs with high mobility, poly-crystalline silicon (poly-Si) TFTs and amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs attract the most attention.Although poly-Si TFT has μ eff close to 100 cm 2 /V s, it requires additional re-crystallization steps such as excimer-laser annealing, metal seeding or solid phase crystallization. These add more complexity and costs to the process. The substrate size used by poly-Si TFT technology is about 4 generations behind what a-Si TFTs can achieve today, while a-IGZO device encounters no special issue when it comes to the glass size. A-IGZO TFTs have many advantages like low temperature process (below 300• C) and high on/off ratio (∼10 6 ). 1 In addition, it is highly transparent in visible light with transmittance over 90% as illustrated due to wide bandgap (∼3 eV).These properties open up to new applications such as transparent electronics, flexible electronics, and photo sensor.2,3 Even though a-IGZO TFTs exhibit good electrical characteristics and stability in the dark state, the significant electrical instability is observed when they are illuminated. Many article reported threshold voltage (V TH ) shift and mobility change after illumination at different light intensities, and those changes can recover in time. 4,5 In the applications of transparent electronics and photo sensor, the a-IGZO TFTs are expected to operate in the transmission of ambient light with frequently varying intensity. In addition, most of the reports studied the change in the devices under for long-time illumination, 6-8 but the response to the illumination ...

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Analyzing the effects of ambient dependence for InGaZnO TFTs under illuminated bias stress

Cited by 9 publications

References 21 publications

The Vacancy Pool Model for Amorphous In-Ga-Zn-O Thin-Film Transistors

The Vacancy Pool Model for Amorphous In-Ga-Zn-O Thin-Film Transistors

Energy band offsets of dielectrics on InGaZnO4

The Time Response of the On-Current for the Amorphous In-Ga-Zn-O Thin Film Transistor to the Illumination Pulse

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