전상훈 교수

Recently, hafnia ferroelectrics with two spontaneous polarization states have attracted marked attention for non-volatile, super-steep switching devices, and neuromorphic application due to their fast switching, scalability, and CMOS compatibility. However, field cycling-induced instabilities are a serious obstacle in the practical application of various low-power electronic devices that require a settled characteristic of polarization hysteresis. In this work, a large reduction in the field cyc

We report on 4.5-nm-thick Hf0.5Zr0.5O2 (HZO) thin-film-based ferroelectric tunnel junctions (FTJs) with a tungsten (W) bottom electrode. The HZO on the W electrode exhibits stable ferroelectricity with a remanent polarization of 14 μC/cm2, an enhanced tunneling electroresistance of 16, and excellent synaptic properties. We found that a large tensile stress was induced on a HZO thin film, owing to a low thermal expansion coefficient of the W bottom electrode. The low thermal expansion coefficient

The photoresponse characteristics of metal-oxide (MeO) semiconductor photosensors have been studied. Compared to the amorphous-Si-based photo-TFT, the MeO photo-TFT demonstrates superior EQE and responsivity. However, due to its inherent slow recovery to the dark state after the illumination is stopped, a unique sensing scheme suitable for the high-speed array operation is used, yet maintaining a simple array architecture as a solution for large-area interactive displays.

Abstract Ferroelectric tunnel junctions (FTJs) have attracted research interest as promising candidates for non-destructive readout non-volatile memories. Unlike conventional perovskite FTJs, hafnia FTJs offer many advantages in terms of scalability and CMOS compatibility. However, so far, hafnia FTJs have shown poor endurance and relatively low resistance ratios and these have remained issues for real device applications. In our study, we fabricated HfZrO(HZO)-based FTJs with various electrodes

The hygroscopic nature of lanthanide oxides such as Pr2O3, Sm2O3, Gd2O3, and Dy2O3 was characterized by means of x-ray photoelectron spectroscopy and its effect on the electrical characteristics of the compounds was investigated. Among the four samples, Pr2O3 was found to be the most reactive with water which can be attributed to the relatively large ionic radius and lower electronegativity of Pr. In contrast, Dy2O3 was the least reactive with water. A direct correlation between the hygroscopici

Electronic skin (e-skin) is designed to mimic the comprehensive nature of human skin. Various advances in e-skin continue to drive the development of the multimodal tactile sensor technology on flexible and stretchable platforms. e-skin incorporates pressure, temperature, texture, photographic imaging, and other sensors as well as data acquisition and signal processing units formed on a soft substrate for humanoid robots, wearable devices, and health monitoring electronics that are the most crit

We present the development of a flexible bimodal sensor using a paper platform and inkjet printing method, which are suited for low-cost fabrication processes and realization of flexible devices. In this study, we employed a vertically stacked bimodal device architecture in which a temperature sensor is stacked on top of a pressure sensor and operated on different principles, allowing the minimization of interference effects. For the temperature sensor placed in the top layer, we used the thermo

The electrical characteristics of ZrOxNy prepared by NH3 annealing of ZrO2 were investigated for use in metal–oxide–semiconductor gate dielectric applications. Compared with conventional ZrO2, ZrOxNy exhibits excellent electrical characteristics such as high accumulation capacitance, low leakage current density, and superior thermal stability. Based on high resolution transmission electron microscope analysis of both ZrO2 and ZrOxNy samples which had been annealed at 800 °C for 5 min, the ZrO2 e

loading/unloading cycles. The temperature sensor combines various materials such as poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), silver nanoparticles (AgNPs) and carbon nanotubes (CNTs) to form a thermocouple on the upper nanocellulose layer. The thermoelectric-based temperature sensors generate a thermoelectric voltage output of 1.7 mV for a temperature difference of 125 K. Our 5 × 5 tactile sensor arrays show a fast response, negligible interference, and durable sensing

Wearable sensor systems with ultra-thinness, light weight, high flexibility, and stretchability that are conformally in contact with the skin have advanced tremendously in many respects, but they still face challenges in terms of scalability, processibility, and manufacturability. Here, we report a highly stretchable and wearable textile-based self-powered temperature sensor fabricated using commercial thermoelectric inks. Through various combinations of poly(3,4-ethylene dioxythiophene)-poly(st

A technique for invisible image capture using a photosensor array based on transparent conducting oxide semiconductor thin-film transistors and transparent interconnection technologies is presented. A transparent conducting layer is employed for the sensor electrodes as well as interconnection in the array, providing about 80% transmittance at visible-light wavelengths. The phototransistor is a Hf-In-Zn-O/In-Zn-O heterostructure yielding a high quantum-efficiency in the visible range.

The integration of electronically active oxide components onto silicon circuits represents an innovative approach to improving the functionality of novel devices. Like most semiconductor devices, complementary-metal-oxide-semiconductor image sensors (CISs) have physical limitations when progressively scaled down to extremely small dimensions. In this paper, we propose a novel hybrid CIS architecture that is based on the combination of nanometer-scale amorphous In-Ga-Zn-O (a-IGZO) thin-film trans

. In terms of thickness scaling, CMOS compatibility, and 3D integration, these fluorite-structured FTJs provide a number of benefits over conventional perovskite-based FTJs. Here, recent developments involving all FTJ devices with fluorite structures are examined. The transport mechanism of fluorite-structured FTJs is explored and contrasted with perovskite-based FTJs and other 2-terminal resistive switching devices starting with the operation principle and essential parameters of the tunneling