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We proposed a novel material named sodium hypochlorite (NaClO) solution as a source of activation for amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). We reduced the activation temperature from 300 to 150 °C using NaClO solution (concentration: 50%) and obtained satisfactory electrical characteristics of a-IGZO TFTs. The field-effect mobility, threshold voltage, on/off ratio, subthreshold swing, and threshold voltage (Vth) shift under negative bias illumination stress (VG = -20 V and VD = 10.1 V for 10,000 s) of NaClO (50%)-activated a-IGZO TFTs were 10.41 cm2/V·s, 1.51 V, 2.78 × 108, 0.37 V/dec, and -5.43 V, respectively. Also, the Vth shifts of the NaClO (50%)-activated a-IGZO TFTs (150 °C) under the positive bias stress test decreased from 5.01 to 1.87 V (VG = 20 V and VD = 10.1 V for 10,000 s) compared with that of only-annealed (300 °C) a-IGZO TFTs. Also, the mechanism of NaClO activation for a-IGZO TFTs is clarified through photo-assisted oxygen radical (POR) and heat-driven oxygen radical (HOR) effects. The POR and HOR effects generated the reactive oxygen species (ROS) from NaClO solution (50%), which activated a-IGZO TFTs at a low temperature (150 °C). When the NaClO solution (50%) was exposed to external energy, it generated ROS such as hydroxyl radicals (OH•), hydroperoxyl radicals (HO2•), and oxygen radicals (O•), which promoted the formation of strong metal-oxide bonds in a-IGZO TFTs. Furthermore, NaClO solution (50%) was applied to a-IGZO TFTs on a flexible polyimide substrate and electrohydrodynamic printing process for selective deposition.

Visible light can be detected using an indium–gallium–zinc oxide (IGZO)-based phototransistor, with a selenium capping layer (SCL) that functions as a visible light absorption layer. Selenium (Se) exhibits photoconductive properties as its conductivity increases with illumination. We report an IGZO phototransistor with an SCL (SCL/IGZO phototransistor) that demonstrated optimal photoresponse characteristics when the SCL was 150 nm thick. The SCL/IGZO phototransistor exhibited a photoresponsivity of 1.39 × 103 A/W, photosensitivity of 4.39 × 109, detectivity of 3.44 × 1013 Jones, and external quantum efficiency of 3.52 × 103% when illuminated by green light (532 nm). Ultraviolet–visible spectroscopy and ultraviolet photoelectron spectroscopy analysis showed that Se has a narrow energy band gap, in which visible light is absorbed and forms a p–n junction with IGZO so that photogenerated electron–hole pairs are easily separated, which makes recombination more challenging. We show that electrons generated in ...

In recent decades, oxide thin-film transistors (TFTs) have attracted a great deal of attention as a promising technology in terms of next-generation electronics due to their outstanding electrical performance. However, achieving robust electrical characteristics under various environments is a crucial challenge for successful realization of oxide-based electronic applications. To resolve the limitation, we propose a highly flexible and reliable heterogeneous organic passivation layer composed of stacked parylene-C and diketopyrrolopyrrole-polymer films for improving stability of oxide TFTs under various environments and mechanical stress. The presented multifunctional heterogeneous organic (MHO) passivation leads to high-performance oxide TFTs by: (1) improving their electrical characteristics, (2) protecting them from external reactive molecules, and (3) blocking light exposure to the oxide layer. As a result, oxide TFTs with MHO passivation exhibit outstanding stability in ambient air as well as under light illumination: the threshold voltage shift of the device is almost 0 V under severe negative bias illumination stress condition (white light of 5700 lx, gate voltage of -20 V, and drain voltage of 10.1 V for 20 000 s). Furthermore, since the MHO passivation layer exhibits high mechanical stability at a bending radius of ≤5 mm and can be deposited at room temperature, this technique is expected to be useful in the fabrication of flexible/wearable devices.

We suggest thermal treatment with static magnetic fields (SMFs) or rotating magnetic fields (RMFs) as a new technique for the activation of indium–gallium–zinc oxide thin-film transistors (IGZO TFTs). Magnetic interactions between metal atoms in IGZO films and oxygen atoms in air by SMFs or RMFs can be expected to enhance metal–oxide (M–O) bonds, even at low temperature (150 °C), through attraction of metal and oxygen atoms having their magnetic moments aligned in the same direction. Compared to IGZO TFTs with only thermal treatment at 300 °C, IGZO TFTs under an RMF (1150 rpm) at 150 °C show superior or comparable characteristics: field-effect mobility of 12.68 cm2 V–1 s–1, subthreshold swing of 0.37 V dec–1, and on/off ratio of 1.86 × 108. Although IGZO TFTs under an SMF (0 rpm) can be activated at 150 °C, the electrical performance is further improved in IGZO TFTs under an RMF (1150 rpm). These improvements of IGZO TFTs under an RMF (1150 rpm) are induced by increases in the number of M–O bonds due to e...

To broaden the availability and application of metal-oxide (M-O)-based optoelectronic devices, we suggest heterogeneous phototransistors composed of In-Ga-Zn-O (IGZO) and methylammonium lead iodide (CH

A homojunction-structured amorphous indium gallium zinc oxide (a-IGZO) phototransistor that can detect visible light is reported. The key element of this technology is an absorption layer composed of hydrogen-doped a-IGZO. This absorption layer is fabricated by simple hydrogen plasma doping, and subgap states are induced by increasing the amount of hydrogen impurities. These subgap states, which lead to a higher number of photoexcited carriers and aggravate the instability under negative bias illumination stress, enabled the detection of a wide range of visible light (400–700 nm). The optimal condition of the hydrogen-doped absorption layer (HAL) is fabricated at a hydrogen partial pressure ratio of 2%. As a result, the optimized a-IGZO phototransistor with the HAL exhibits a high photoresponsivity of 1932.6 A/W, a photosensitivity of 3.85 × 106, and a detectivity of 6.93 × 1011 Jones under 635 nm light illumination.