Abnormal hump in capacitance–voltage measurements induced by ultraviolet light in a-IGZO thin-film transistors

Tsao, Yao-Chung; Chang, Ting Chang; Chen, Hua Mao; Chen, Bo Wei; Chiang, Hsiao Cheng; Chen, Guan Fu; Chien, Yu‐Chieh; Tai, Ya‐Hsiang; Hung, Yu Ju; Huang, Shin Ping; Yang, Chin‐Yi; Chou, Wu–Ching

doi:10.1063/1.4973856

Cited by 18 publications

(4 citation statements)

References 19 publications

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“…However, single-crystal IGZO growth with mobility of 80 cm 2 V –1 s –1 is reported by thermal annealing of IGZO at a temperature of 700–1000 °C . The annealing temperature of crystallization may differ depending on the film preparation technique, but on average, amorphous IGZO deposited at room temperature requires thermal annealing at 600–700 °C to convert it to a polycrystalline phase . Another important issue is the thermal conductivity of IGZO (1.4 W m –1 K –1 ), which is significantly lower than the polycrystalline silicon (32 W m –1 K –1 ); this can cause self-induced thermal degradation of IGZO devices.…”

Section: Introductionmentioning

confidence: 99%

Femtosecond Laser-Induced Crystallization of Amorphous Silicon Thin Films under a Thin Molybdenum Layer

Farid

Brunton

Rumsby

et al. 2021

ACS Appl. Mater. Interfaces

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A new process to crystallize amorphous silicon without melting and the generation of excessive heating of nearby components is presented. We propose the addition of a molybdenum layer to improve the quality of the laser-induced crystallization over that achieved by direct irradiation of silicon alone. The advantages are that it allows the control of crystallite size by varying the applied fluence of a near-infrared femtosecond laser. It offers two fluence regimes for nanocrystallization and polycrystallization with small and large crystallite sizes, respectively. The high repetition rate of the compact femtosecond laser source enables high-quality crystallization over large areas. In this proposed method, a multilayer structure is irradiated with a single femtosecond laser pulse. The multilayer structure includes a substrate, a target amorphous Si layer coated with an additional molybdenum thin film. The Si layer is crystallized by irradiating the Mo layer at different fluence regimes. The transfer of energy from the irradiated Mo layer to the Si film causes the crystallization of amorphous Si at low temperatures (∼700 K). Numerical simulations were carried out to estimate the electron and lattice temperatures for different fluence regimes using a two-temperature model. The roles of direct phonon transport and inelastic electron scattering at the Mo–Si interface were considered in the transfer of energy from the Mo to the Si film. The simulations confirm the experimental evidence that amorphous Si was crystallized in an all-solid-state process at temperatures lower than the melting point of Si, which is consistent with the results from transmission electron microscopy (TEM) and Raman. The formation of crystallized Si with controlled crystallite size after laser treatment can lead to longer mean free paths for carriers and increased electrical conductivity.

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Section: Introductionmentioning

confidence: 99%

Femtosecond Laser-Induced Crystallization of Amorphous Silicon Thin Films under a Thin Molybdenum Layer

Farid

Brunton

Rumsby

et al. 2021

ACS Appl. Mater. Interfaces

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“…Many metal‐oxide‐based materials have been used, such as ZnO, ZnMgO, ZnSnO, and InMgO, which directly serve as the active channel in the TFT structure for their clear response to UV light illumination . In industry, the metal oxide composition material InGaZnO 4 (IGZO) was originally proposed for display applications . Due to its high transparency, uniformity, and mobility, IGZO has significant attention for various applications and their related TFT reliability issues .…”

Section: Comparisons Of the Features Of Many Other Uv Sensing Devicesmentioning

confidence: 99%

A Dual‐Gate InGaZnO₄‐Based Thin‐Film Transistor for High‐Sensitivity UV Detection

Chen

Tsao

Chien

et al. 2019

Adv Materials Technologies

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produces some real risks, including wrinkles, pigmented flat spots known as liver spots, and even skin cancer. [1][2][3][4] These are mostly attributed to the effects of UV light, a shorter wavelength than the visual spectrum. Therefore, over the past decades, developments in UV sensors have received significant attention for their potential positive effects on human health.When considering the performance of many different UV sensors, required features include high sensitivity, stability, and linearity. Most importantly, a compact design compatible with current device fabrication process is key for low-cost production. [5,6] Previous studies mostly focused on a two terminal photodiode device based on wide bandgap (WBG) semiconductor materials such as TiO 2 , SiC, and ZnO materials. [7][8][9] Later, some III-V compounds, such as gallium nitride (GaN), also received attention as UV photodetector materials. [10,11] Some metal-semiconductor-metal (MSM) structures have also been proposed to simplify device fabrication processes. [7][8][9][10][11][12] Although such WBG-based UV sensors have the advantages of a simple structure and high intrinsic visible-blindness; numinous drawbacks such as poor crystal quality or high activation energy of dopants have slowed developments. In addition, UV-sensing devices have received significant recent attention for applications in areas such as human health, fire detection, and optical communication.One key factor for product commercialization is determining the optimal materials that allow for integration of excellent UV-sensing properties with compatibility with industrial fabrication processes. However, current UV sensors often fail to achieve this due to either mismatched materials or a device that must be excessively large in order to produce enough photocurrent for UV detection. The UV-light-sensing properties of an amorphous InGaZnO 4 (IGZO) thin-film transistor with a dual-gate structure and relatively small device size (width/length = 50 μm/10 μm) that achieves high sensitivity through a threshold-voltage-(V th )-adjustment method is proposed. Comparing the drain currents under UV exposure to those under darkened conditions indicates that the ratio between the photoinduced and dark current reaches 10 6 . Furthermore, the UV sensitivity of the dual-gate transistors can be adjusted by varying the bottom gate voltage, with each pixel of the sensor then being read out separately via scan line pulses. This allows the dual-gate a-IGZO transistor to be used for high-performance UV sensing while being effectively integrated in display applications. SensorsAlmost all living things on Earth rely on the sun for nutrition and survival, whether directly or indirectly. The sun provides radiant heat, and gives energy to plants for the photosynthesis process, thus providing basic needs and food for creatures and humans. However, exposure to the sun for human beings also

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“…The driving long-term stability in the oxide semiconductor has been studied from various perspectives: charge trapping 4 , defect creation 5 , ambient effect 6 , impact ionization 3 , and hot carrier injection 7 . Among these causes, the common phenomenon observed is the “ hump ” characteristic in the current–voltage (I–V) 8–10 or capacitance–voltage (C–V) 11 measurement.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the hump phenomenon and needle defect states formed by driving stress in the oxide semiconductor

Lee

Abe²,

Noh

et al. 2019

Sci Rep

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The reduction in current ability accompanied by the hump phenomenon in oxide semiconductor thin-film transistors to which high DC voltages and AC drive voltages are applied has not been studied extensively, although it is a significant bottleneck in the manufacture of integrated circuits. Here, we report on the origin of the hump and current drop in reliability tests caused by the degradation in the oxide semiconductor during a circuit driving test. The hump phenomenon and current drop according to two different driving stresses were verified. Through a numerical computational simulation, we confirmed that this issue can be caused by an additional “ needle ”, a shallow (~0.2 eV) and narrow (<0.1 eV), defect state near the conduction band minimum (CBM). This is also discussed in terms of the dual current path caused by leakage current in the channel edge.

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Abnormal hump in capacitance–voltage measurements induced by ultraviolet light in a-IGZO thin-film transistors

Cited by 18 publications

References 19 publications

Femtosecond Laser-Induced Crystallization of Amorphous Silicon Thin Films under a Thin Molybdenum Layer

Femtosecond Laser-Induced Crystallization of Amorphous Silicon Thin Films under a Thin Molybdenum Layer

A Dual‐Gate InGaZnO₄‐Based Thin‐Film Transistor for High‐Sensitivity UV Detection

Analysis of the hump phenomenon and needle defect states formed by driving stress in the oxide semiconductor

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Abnormal hump in capacitance–voltage measurements induced by ultraviolet light in a-IGZO thin-film transistors

Cited by 18 publications

References 19 publications

Femtosecond Laser-Induced Crystallization of Amorphous Silicon Thin Films under a Thin Molybdenum Layer

Femtosecond Laser-Induced Crystallization of Amorphous Silicon Thin Films under a Thin Molybdenum Layer

A Dual‐Gate InGaZnO4‐Based Thin‐Film Transistor for High‐Sensitivity UV Detection

Analysis of the hump phenomenon and needle defect states formed by driving stress in the oxide semiconductor

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A Dual‐Gate InGaZnO₄‐Based Thin‐Film Transistor for High‐Sensitivity UV Detection