Effect of Simultaneous Mechanical and Electrical Stress on the Electrical Performance of Flexible In-Ga-Zn-O Thin-Film Transistors

Seo, Youngjin; Jeong, Hwan-Seok; Jeong, Ha-Yun; Park, Shinyoung; Jang, Jun Tae; Kim, Dong Myong; Choi, Sung-Jin; Jin, Xiaoshi; Kwon, Hyuck‐In; Kim, Dae Hwan

doi:10.3390/ma12193248

Cited by 17 publications

(15 citation statements)

References 34 publications

(39 reference statements)

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“…Therefore, the TFTs exhibited high electrical stability. [ 42,43 ] Figure 5e,f show the electrical stability of the oxide TFTs under the PBIS and NBIS, respectively. The samples were subjected to an illumination of 0.5 mW cm –2 under a gate bias stress.…”

Section: Resultsmentioning

confidence: 99%

Ultrathin, Flexible, and Transparent Oxide Thin‐Film Transistors by Delamination and Transfer Methods for Deformable Displays

Lee

et al. 2021

Adv Materials Technologies

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applications such as in wearable devices, glasses of transportation and buildings, and mirrors. [1][2][3] The transparent organic light-emitting diodes (OLEDs) and microlight emitting diodes (micro-LEDs) are the optimal candidates among the various display devices for the aforementioned applications. This is attributed to the outstanding performances and relatively high power efficiencies of the OLEDs and micro LEDs. [4,5] Furthermore, backplane devices play a critical role in the development of next-generation displays.Thin-film transistors (TFTs) are utilized as the backplane devices for active matrix (AM) liquid-crystal displays, AM organic light-emitting diode (AMOLED) displays, AM-LEDs, and quantum-dot LEDs. TFTs with amorphous oxide semiconductors are suitable candidates for such applications owing to their multiple advantages such as ease of fabrication, high electron mobility, high electrical stability, and uniformity over a large area. [6,7] Therefore, it is necessary to develop flexible and transparent oxide TFTs that exhibit outstanding electrical performances. Furthermore, it is essential to design ultrathin display devices to ensure their complete coverage on and attachment to various objects including stretchable substrates.A typical fabrication method for flexible oxide TFTs includes a direct formation of film on a plastic substrate by a vapor deposition, solution spinning, or bar coating, followed by photopatterning. [8][9][10] However, most of the transparent plastic films, including polyethylene terephthalate (PET) exhibit a high coefficient of thermal expansion and a low glass transition temperature (T g ). [11] These characteristics hinder the optimization of the electrical performance of the oxide thin films that can be achieved by post-annealing at high temperatures. Furthermore, they also prevent the high-density integration of devices. To address these drawbacks, extensive research has been conducted on the application of heat-resistant plastic films like polyimide as flexible substrates. [12][13][14] However, these films exhibit a low optical transparency owing to their yellowish appearance. Although the colorless polyimide can be processed at 300 °C as a substrate for oxide TFTs, the thick thickness (>10 µm) of such devices prevents their applications to substrates with diverse surface profiles.To alleviate these issues, ultrathin flexible devices were prepared by a technique involving delamination and transfer, where the TFT arrays were delaminated from a rigid substrate

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Section: Resultsmentioning

confidence: 99%

Ultrathin, Flexible, and Transparent Oxide Thin‐Film Transistors by Delamination and Transfer Methods for Deformable Displays

Lee

et al. 2021

Adv Materials Technologies

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“…In particular, oxygen deficiencies serve as shallow donors of free electrons in the conduction band [ 25 ]. The increased donor-like states due to the ionized oxygen vacancies induce a negative shift in the threshold voltage [ 22 , 26 ]. When different levels of strain are applied to the a-IGZO layer, the corresponding changes in the trap states are different.…”

Section: Resultsmentioning

confidence: 99%

“…The degradation of a-IGZO TFTs under bending stress has been studied extensively under various bending stress conditions, namely tensile or compressive stress [ 6 , 12 , 13 ]; bending direction perpendicular or parallel bending to the current flow [ 14 , 15 ]; bending radius [ 16 , 17 , 18 ]; and bending cycles [ 19 , 20 ]. Several research groups have extracted the density of states of the active layer by conducting computer-aided design simulations and verified that the number of donor-like trap states increases with repeated bending [ 15 , 21 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

New Simulation Method for Dependency of Device Degradation on Bending Direction and Channel Length

2021

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The dependency of device degradation on bending direction and channel length is analyzed in terms of bandgap states in amorphous indium-gallium-zinc-oxide (a-IGZO) films. The strain distribution in an a-IGZO film under perpendicular and parallel bending of a device with various channel lengths is investigated by conducting a three-dimensional mechanical simulation. Based on the obtained strain distribution, new device simulation structures are suggested in which the active layer is defined as consisting of multiple regions. The different arrangements of a highly strained region and density of states is proportional to the strain account for the measurement tendency. The analysis performed using the proposed structures reveals the causes underlying the effects of different bending directions and channel lengths, which cannot be explained using the existing simulation methods in which the active layer is defined as a single region.

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“…12 Seo et al fabricated flexible In-Ga-Zn-O TFTs on PET substrate with fieldeffect mobility of 7.3 cm 2 /Vs. 13 The effects of tensile and compressive bending stress on flexible a-IGZO TFTs performance have been reported. 14 We have fabricated enhanced performance ZnO channel/Al2O3 gate insulator TFTs by ALD continuous growth process.…”

Section: Introductionmentioning

confidence: 99%

36.3: Flexible ZnO Thin‐Film Transistors Fabricated on PEN Substrate by Atomic Layer Deposition at Low Temperature

Dong

et al. 2021

Symp Digest of Tech Papers

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Flexible ZnO thin‐film transistors (TFTs) have been successfully fabricated by atomic layer deposition (ALD) on polyethylene naphthalate (PEN) substrate with a maximum processing temperature of 200 °C. The flexible ZnO TFTs show competitive electrical properties with high saturation mobility (μsat) of 17.5 cm2/Vs, small subthreshold slope (SS) of 91 mV/dec, high Ion/Ioff of 3.8×109 and good uniformity. The larger characteristic trapping time τ for flexible ZnO TFT under NBS is the indication of less trapped charges compared with the device under PBS. In addition, we also investigate the mechanical bending test of flexible ZnO TFTs. The flexible ZnO TFTs exhibit a negative turn‐on voltage (Von) shift and degraded SS with increasing tensile strains because the mechanical strain at the bending part of TFT channel generates donor‐like and acceptor‐like defects. Our results demonstrate that ALD process flexible ZnO TFTs exhibiting tremendous potential to be applicable in flexible electronics.

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Effect of Simultaneous Mechanical and Electrical Stress on the Electrical Performance of Flexible In-Ga-Zn-O Thin-Film Transistors

Cited by 17 publications

References 34 publications

Ultrathin, Flexible, and Transparent Oxide Thin‐Film Transistors by Delamination and Transfer Methods for Deformable Displays

Ultrathin, Flexible, and Transparent Oxide Thin‐Film Transistors by Delamination and Transfer Methods for Deformable Displays

New Simulation Method for Dependency of Device Degradation on Bending Direction and Channel Length

36.3: Flexible ZnO Thin‐Film Transistors Fabricated on PEN Substrate by Atomic Layer Deposition at Low Temperature

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