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 × 10, and a detectivity of 6.93 × 10 Jones under 635 nm light illumination.
Memory for skin-attachable wearable devices for healthcare monitoring must meet a number of requirements, including flexibility and stability in external environments. Among various memory technologies, organic-based resistive random-access memory (RRAM) devices are an attractive candidate for skin-attachable wearable devices due to the high flexibility of organic materials. However, organic-based RRAMs are particularly vulnerable to external moisture, making them difficult to apply as skin-attachable wearable devices. In this research, RRAMs are fabricated that meet the requirements for skinattachable wearable devices using a novel organic material, nitrocellulose (NC), which is biocompatible with high water-resistance and high flexibility. The fabricated NC-based RRAMs show a stable bipolar resistive switching characteristic. In addition, the formation of a native Al oxide between Al and NC is verified, which is the source of the bipolar switching characteristic of NC-based RRAMs. Furthermore, electrical and chemical analysis is conducted after dipping and submersion into various solutions as well as deionized water to confirm the water-resistance of the NC-based RRAMs. Finally, it is also confirmed that NC-based RRAMs are suitable for use in skin-attachable wearable devices through a flexibility test. In conclusion, this study suggests that NC-based RRAMs can be applied in skin-attachable wearable devices, simplifying healthcare in the future.
Resistive random access memory (RRAM) devices are fabricated through a simple solution process using glucose, which is a natural biomaterial for the switching layer of RRAM. The fabricated glucose-based RRAM device shows nonvolatile bipolar resistive switching behavior, with a switching window of 10 . In addition, the endurance and data retention capability of glucose-based RRAM exhibit stable characteristics up to 100 consecutive cycles and 10 s under constant voltage stress at 0.3 V. The interface between the top electrode and the glucose film is carefully investigated to demonstrate the bipolar switching mechanism of the glucose-based RRAM device. The glucose based-RRAM is also evaluated on a polyimide film to verify the possibility of a flexible platform. Additionally, a cross-bar array structure with a magnesium electrode is prepared on various substrates to assess the degradability and biocompatibility for the implantable bioelectronic devices, which are harmless and nontoxic to the human body. It is expected that this research can provide meaningful insights for developing the future bioelectronic devices.
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 (CHNHPbI) layers, which act as the amplifier layer (channel layer) and absorption layer, respectively. These heterogeneous phototransistors showed low persistence photocurrent compared with IGZO-only phototransistors and exhibited high photoresponsivity of 61 A/W, photosensitivity of 3.48 × 10, detectivity of 9.42 × 10 Jones, external quantum efficiency of 154% in an optimized structure, and high photoresponsivity under water exposure via the deposition of silicon dioxide as a passivation layer. On the basis of these electrical results and various analyses, we determined that CHNHPbI could be activated as a light absorption layer, current barrier, and plasma damage blocking layer, which would serve to widen the range of applications of M-O-based optoelectronic devices with high photoresponsivity and reliability under visible light illumination.
We explored the effects of hypochlorous acid (HClO) oxidation on p-type oxide semiconductors. HClO generates oxygen radicals (O·) (strong reactive oxygen species) that affect the chemical state of p-type copper oxide (CuO ) thin films by reacting with CuO. On robust oxidation by HClO, the numbers of Cu-O bonds increased and the numbers of copper vacancies serving as hole carriers decreased. In the modified CuO thin-film transistors (TFTs), switching was evident. The subthreshold swing was 0.70 V/dec, the on-/off-current ratio was 4.86 × 10, and the field effect mobility was 2.83 × 10 cm/V·s. Pristine CuO TFTs did not exhibit switching.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.