Chang-Ki Baek

Chang-Ki Baek
Pohang University of Science and Technology | POSTECH · Department of Convergence IT Engineering

Ph. D

About

149
Publications
11,456
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,660
Citations
Citations since 2017
58 Research Items
1311 Citations
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
Introduction
Research Interest ◆ Silicon Nanowire based photovolatic, thermoelectric devices and sensor application ◆ Theoretical Modeling and 3D Quantum Simulation of Nanoscale Devices ◆ Advanced Nanoscale Logic and Memory Devices(DRAM and Flash Cell) Homepage: idea.postech.ac.kr (Lab)
Additional affiliations
February 2018 - September 2018
Pohang University of Science and Technology
Position
  • Professor (Assistant)
February 2014 - present
Pohang University of Science and Technology
Position
  • Professor (Associate)
September 2010 - January 2014
Pohang University of Science and Technology
Position
  • Research Assistant

Publications

Publications (149)
Article
Full-text available
Three-terminal (3-T) thyristor random-access memory is explored for a next-generation high-density nanoscale vertical cross-point array. The effects of standby voltages on the device are thoroughly investigated in terms of gate–cathode voltage ( V GC,ST ) and anode–cathode voltage ( V AC,ST ) in the standby state for superior data retention charact...
Article
A drain-extended (De) FinFET (DeFinFET) with a high-k dielectric field plate is proposed for high-voltage (HV) system-on-chip (SoC) applications at 10-nm CMOS technology nodes. Conventional DeFinFETs without the dielectric field plate and DeFinFETs with SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlin...
Article
Full-text available
Silicon photodiodes are widely used in applications that require the measurement of the intensity, colour and position of visible light. Silicon is an attractive material for these systems owing to its low cost, low noise, and easy on-chip integration with read-out electronics. However, silicon cannot effectively be used to detect near-infrared (NI...
Article
Thermoelectric modules based on silicon nanowires (Si-NWs) have recently attracted significant attention as they show improved thermoelectric efficiency due to a decrease in thermal conductivity. Here, we adopt a top-down fabrication method to dramatically reduce the thermal conductivity of vertical Si-NWs. The thermal conductivity of vertical Si-N...
Article
Electrolyte-insulator-semiconductor (EIS) sensor is commonly considered for chemical and biosensing applications due to its small size and simple fabrication method. Here, we demonstrate a fluoride-sensitive EIS sensor using thermally-deposited polycrystalline lanthanum fluoride (poly LaF3) film as sensing membrane, which is cheaper than single-cry...
Article
Chemical sensors are an essential part of modern society to ensure safety, from preventing pollution to saving lives. Especially, the demand for real-time monitoring of hydrogen fluoride (HF) increases continuously due to its high toxicity, contrary to its wide use in industries. In addition, compact size and low cost are favorable to utilize the s...
Article
Full-text available
The simple structure, low power consumption, and small form factor have made surface acoustic wave (SAW) devices essential to mobile communication as RF filters. For instance, the latest 5G smartphones are equipped with almost 100 acoustic wave filters to select a specific frequency band and increase communication capacity. On the arrival of the ne...
Article
Full-text available
A drain-extended (DE) FinFET with a dual material gate (DMG) and a high-k field plate (FP), named DF-DeFF, is proposed for high-voltage RF applications. The FP induces the charge variation in the drain extension, which appears as either the extended depletion in the gate-off state or the electron accumulation in the gate-on state. Along with the FP...
Preprint
Full-text available
Immunotherapy using CAR-T cells is a new paradigm technology for cancer treatment. To avoid severe side effects and tumor escape variants observed for conventional CAR-T cells approach, adaptor CAR technologies are under development, where intermediate target modules redirect immune cells against cancer. In this work, silicon nanowire field effect...
Preprint
Full-text available
Three-terminal (3-T) thyristor random-access memory is explored for a next generation high-density nanoscale vertical cross-point array. The effects of standby voltages on the device are thoroughly investigated in terms of gate-cathode voltage ( V GC,ST ) and anode- cathode voltage ( V AC,ST ) in the standby state for superior data retention charac...
Preprint
Full-text available
Three-terminal (3-T) thyristor random-access memory is explored for a next generation high-density nanoscale vertical cross-point array. The effects of standby voltages on the device are thoroughly investigated in terms of gate-cathode voltage ( V GC,ST ) and anode- cathode voltage ( V AC,ST ) in the standby state for superior data retention charac...
Article
Silicon nanowires (SiNWs) have attracted attention as promising high efficiency thermoelectric materials by significantly improving the thermoelectric efficiency of silicon. Here, we have fabricated cobalt silicide/silicon heterostructure on both ends of nanowires using self-aligned silicide (salicide) process. By forming cobalt silicide (CoSi2) la...
Article
Full-text available
Two-terminal (2-T) thyristor random access memory (TRAM) based on nanoscale cross-point vertical array is investigated in terms of lengths and doping concentrations of storage regions for long data retention time (Tret). For high device scalability and low program voltage (VP), lengths of the storage regions are determined by the sum of depletion w...
Article
Small molecules with no or little charge are considered to have minimal impact on signals measured by field effect transistor (FET) sensors. This fact typically excludes steroids from the family of analytes, detected by FETs. We present a portable multiplexed platform based on an array of nanowire sensors for label-free monitoring of daytime levels...
Article
Full-text available
[Full text: https://rdcu.be/b4ovR] Neuromorphic architectures merge learning and memory functions within a single unit cell and in a neuron-like fashion. Research in the field has been mainly focused on the plasticity of artificial synapses. However, the intrinsic plasticity of the neuronal membrane is also important in the implementation of neurom...
Article
Full-text available
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Article
We report the reduction of thermal conductivity and phonon mean-free-path below the Casimir limit originated by phonon backscattering in silicon nanowires with scallop shaped surface modulation. The scallop surface modulation with a period of 55–110 nm on 200 nm diameter nanowires was created using top-down deep-reactive-ion-etching. The measured t...
Article
Using calculations from first principles, the site disorder between Ga and Zn of crystalline InGaZnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> is shown to play key roles in its unique transport properties. The analysis based on Density Functional Theory reveals that the various types of s...
Article
In the above-maned article [ibid., vol. 10, no. 2, pp. 475– 479, Mar. 2020], the author Kihyun Kim's affiliation is modified from "the Future IT Innovation Laboratory, Department of Creative IT Engineering, Pohang University of Science and Technology, Pohang 37673, South Korea (kihyun.kim@postech.ac.kr)." to "Division of Electronic Engineering, Jeo...
Article
Full-text available
Despite the recent progress in the synthesis of crystalline boronate ester covalent organic frameworks (BECOFs) in powder and thin‐film through solvothermal method and on‐solid‐surface synthesis, respectively, their applications in electronics, remain less explored due to the challenges in thin‐film processability and device integration associated...
Article
Despite the recent progress in the synthesis of crystalline boronate ester covalent organic frameworks (BECOFs) in powder and thin‐film through solvothermal method and on‐solid‐surface synthesis, respectively, their applications in electronics, remain less explored due to the challenges in thin‐film processability and device integration associated...
Article
Polycrystalline (poly) lanthanum fluoride (LaF3) Electrolyte-Insulator-Semiconductor (EIS) sensors can serve as a promising portable sensor platform for monitoring fluoride ion (F⁻) concentration due to their small size, fast response and simple fabrication method. The key to successful implementation is to consider and understand the effects of th...
Article
Silicon nanowires (SiNWs) are promising structures with excellent photovoltaic properties for low-cost, high-efficiency solar cells and have the potential to overcome the limits of bulk silicon solar cells. There is still a need to enhance light absorption in SiNWs without increasing the surface area. Here, we introduce a novel design, hourglass-sh...
Conference Paper
Full-text available
We propose a hybrid device substituting the software synapse in artificial neural networks with an individual hardware transistor unit. The unit merges a silicon nanowire semiconductor channel with a metal-ion doped solgel film as hybrid gate of the transistor. The film, amorphous and transparent, shows a memristive property due to ion redistributi...
Article
A silicon-based laser is a critical component in the realization of full silicon (Si) photonic integrated circuits due to advantages in cost-competitive integration with the mature digital technology. The poor optical gain stemming from the indirect energy band structure of Si, however, has been a hurdle to realize this goal. An efficient Si nanoca...
Article
Zinc oxide nanowire (ZnO NW) gas sensor with single Schottky contact is capable of sensitive detection of gas molecules. In this study, we investigate the effect of design factors such as nanowire defect density, diameter, and length on the gas sensitivity using 3-D numerical simulation. The sensor with lower defect density or smaller NW diameter e...
Article
Full-text available
Miniaturized and cost-efficient methods aiming at high throughput analysis of microbes is of
Article
We demonstrate high responsivity in a polysilicon (Poly-Si) near-infrared photodetector by reducing the adverse effects of grain boundaries. The presence of grain boundaries is a serious problem in polysilicon since they act as traps and degrade the electrical characteristics. However, the relation between grain boundaries and photodetector perform...
Article
DC characteristics of n-type SiGe heterojunction nanowire tunneling field-effect transistors (TFETs) adopting a core-shell structure are investigated using 3-D numerical simulation. Different mole fractions between the core and the shell regions induce strain effects along the nanowire, which modulate the energy bandgap and thus the dc performance...
Article
Full-text available
Miniaturized and cost-efficient methods aiming at high throughput analysis of microbes is of great importance for the surveillance and control of infectious diseases and the related issue of antimicrobial resistance. Here we demonstrate a miniature nanosensor chip based on a honeycomb-patterned silicon nanowire field effect transistor (FET) capable...
Article
Full-text available
We report the first observation of negative photoconductance (NPC) in n- and p-doped Si nanowire field-effect transistors (FETs) and demonstrate the strong influence of doping concentrations on the nonconventional optical switching of the devices. Furthermore, we show that the NPC of Si nanowire FETs is dependent on the wavelength of visible light...
Article
Nano-helical array of p-NiO/n-SnO2 p-n junctions with well-defined and highly-gas-accessible hetero-interfaces is presented for designable and highly selective gas sensors. The gas sensor having the nanoscale p-n junction sensing layer with a top-and-bottom electrodes configuration was fabricated by conventional photolithography and oblique-angle d...
Presentation
Silicon is the most widely used material for various applications, such as electronic devices, solar cells, and micro-electro-mechanical-systems due to abundant reserves and low cost. Nevertheless, it has not considered as thermoelectric material because of its relatively low thermoelectric efficiency due to high thermal conductivity of 120 W/m∙K....
Presentation
A study of responsivity on photodetector with Poly-Si layer deposited by LPCVD according to doping concentration.
Article
Full-text available
We demonstrate the direct biosensing of the Ebola VP40 matrix protein, using a memristor mode of a liquid-integrated nanodevice, based on a large array of honeycomb-shaped silicon nanowires. To shed more light on the principle of biodetection using memristors, we engineered the opening of the current-minima voltage gap VGAP by involving the third g...
Conference Paper
Tunneling field-effect transistor (TFET) is one of the promising alternatives to substitute the conventional MOSFETs for ultra-low power applications. TFETs can attain the subthreshold swing (SS) below 60 mV/dec for a few orders of drain currents by following band-to-band tunneling instead of thermionic emission transport. However, it is difficult...
Article
DC characteristics of polysilicon nanowire tunneling field-effect transistors (poly-Si NW TFETs) are investigated when a single grain boundary (SGB) existed in the channel region. Poly-Si NW TFETs are analyzed using 3-D numerical simulations in terms of different location and size of the SGB. As the SGB is closer to the source/channel junction, lon...
Article
Wavelength-selective absorption phenomena of silicon-based vertical nanowire (NW) photodetectors (PDs) are investigated using 3-D numerical simulations. The difference in the refractive indexes between silicon NW and its surrounding material induces diameter-dependent waveguide effects at several specific wavelengths for asymmetric as well as symme...
Article
Inversion-mode (IM) and depletion-mode (DM) ion-sensitive field effect transistors (ISFETs) are investigated in terms of dc characteristics, pH response and low-frequency noise (LFN) characteristics. The dc characteristics show a low threshold voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">...
Presentation
Thermal conductivity is one of the most important indicators for evaluating the performance of thermoelectric devices. Thermal conductivity of bulk materials can be measured by flash flash method and flat plate heat flow method, and there are already commercially available products. On the other hand, thermal conductivity measurement of thin film m...
Article
DC/AC performance and the variations due to single interface trap of the nanowire FETs were investigated in the 7-nm technology node using fully-calibrated TCAD simulation. Shorter junction gradient and greater diameter reduced RC delay without short channel degradations. Spacer with smaller dielectric constants decreased parasitic and gate capacit...
Article
Full-text available
We propose three-terminal core-shell (CS) silicon vertical nanowire tunneling field-effect transistors (TFETs), which can be fabricated by conventional CMOS technology. CS TFETs show lower subthreshold swing (SS) and higher on-state current than conventional TFETs through their high surface-to-volume ratio, which increases carrier-tunneling region...
Article
Optimization of operation conditions for biosensing is investigated for the doped silicon nanowire channel transistor sensors. Sensors with phosphorus doped honeycomb nanowire channel are fabricated on 8-inch wafer using conventional CMOS technology. From the low frequency noise (LFN) characteristics, the noise equivalent gate voltage fluctuation i...
Article
Process-induced variations of 10-nm node n-type FinFETs considering middle-of-line parasitics were investigated in terms of dc/ac performances using fully calibrated TCAD simulations. Variations of positive fixed oxide charge density at shallow trench isolation interface and source/drain (S/D) height influenced off-state and on-state performance va...
Conference Paper
Vertical Si nanowire (NW) structure is applicable to a variety of applications such as field-effect transistors (FETs), photodetectors (PDs), and nonvolatile memory because of its high surface-to-volume ratio and quantum effects. Among these, statistical variability study of NWFETs induced by random dopant fluctuation and electrical/optical propert...
Article
Full-text available
Random dopant fluctuation effects of gate-all-around Si nanowire field-effect transistors (FETs) are investigated in terms of different diameters and junction gradients. The nanowire FETs with smaller diameters or shorter junction gradients increase relative variations of the drain currents and the mismatch of the drain currents between source-drai...
Article
In this brief, we systematically investigated the effects of fin pitch (FP) and fin height ( $H_{textrm {fin}}$ ) on parasitic resistances and capacitances to achieve the best $RC$ delay, which is an adequate metric of the ac behavior of FinFETs, for Si bulk n/pFinFETs in system-on-a-chip applications. The $RC$ delays were directly extracted from t...
Article
DC/AC characteristics of Si bulk FinFETs including middle-of-line levels are precisely investigated using well-calibrated 3-D device simulations for system-on-chip applications. Scaling the fin widths down to 5 nm effectively enhances gate-to-channel controllability and improves delay, but a dramatic increase in band-to-band tunneling currents from...
Article
Gas sensors based on metal-oxide-semiconductor transistor with the polysilicon gate replaced by a gas sensitive thin film have been around for over 50 years. These are not suitable for the emerging mobile and wearable sensor platforms due to operating voltages and powers far exceeding the supply capability of batteries. Here we present a novel appr...
Article
Effects of single grain boundary (SGB) and random interface traps (RITs) on the electrical characteristics of the macaroni structure in sub-30 nm poly-silicon (poly-Si) channel devices are analyzed using 3D simulation. The macaroni structure can mitigate the adverse effects of SGB on the electrical variations compared to the conventional structure....
Article
Full-text available
We perform a comparative study of the threshold voltage (Vth) variation between inversion-mode and junctionless nanowire devices with oblique single grain boundary (o-SGB) in a sub-40 nm poly-silicon (Poly-Si) channel using 3D simulation. The Vth variation due to the o-SGB becomes significant as the devices scale down to 20 nm where the o-SGB can f...
Article
Full-text available
Improving the efficiency of solar cells through novel materials and devices is critical to realize the full potential of solar energy to meet the growing worldwide energy demands. We present here a highly efficient radial p-n junction silicon solar cell using an asymmetric nanowire structure with a shorter bottom core diameter than at the top. A ma...
Article
Random dopant fluctuation effects of gate-all-around inversion-mode silicon nanowire field-effect transistors (FETs) with different diameters and extension lengths are investigated. The nanowire FETs with smaller diameter and longer extension length reduce average values and variations of subthreshold swing and drain-induced barrier lowering, thus...
Conference Paper
In this work, the oblique single grain boundary (oSGB) in 3D NAND unit cells is simulated with various temperatures to study threshold voltage (Vth) variation due to oSGB in 3D NAND unit cell of poly-Si channel. As the temperature increases, the overall Vth variations with oSGB decrease because of thermionic effect and more free carrier from genera...
Article
Ion-sensitive field effect transistors have been advanced in recent years by utilizing silicon nanowires (Si-NWs), but establishing their optimized operation regime is an area of ongoing research. We propose a modified configuration of SiNWs in the form of a honeycomb structure to obtain high signal to noise ratio and high current stability. The lo...
Article
The generation and recovery of the interface trap under the Fowler Nordheim (FN) stress in pMOSFETs are measured under various temperatures by extracting the subthreshold swing, and are compared with negative bias temperature instability (NBTI) measurements. The relaxation of the interface trap density is especially analysed in the framework of a u...
Article
The electronic and photoconductive characteristics of CdTe nanowire based field effect transistors were studied systematically. The electrical characterization of a single CdTe nanowire FET verifies p-type behavior. The CdTe NW FETs respond to visible-near infrared (400-800 nm) incident light with a fast, reversible and stable response characterize...
Article
Vertical gate-all-around (GAA) junctionless nanowire transistors (JNTs) with different diameters and underlap lengths are investigated using three-dimensional device simulations. The source-side diameter determines the on-current and drain-induced barrier lowering characteristics, whereas the drain-side diameter controls the band-to-band tunneling...
Article
The photoresponse characteristics of In2Se3 nanowire photodetectors with the κ-phase and α-phase structures are investigated. The as-grown κ-phase In2Se3 nanowires by the vapor-liquid-solid technique are phase-transformed to the α-phase nanowires by thermal annealing. The photoresponse performances of the κ-phase and α-phase In2Se3 nanowire photode...
Article
We investigate the effect of single grain boundary (SGB) with arbitrary angles on the threshold voltage ( (V_{rm {th}}) ) variation in sub-50-nm polysilicon (poly-Si) channel devices using 3-D simulation. An SGB in the poly-Si channel causes changes in potential barrier profile resulting in the variation of (V_{rm {th}}) . As the planar devices sca...
Conference Paper
In this paper, a method to extract the signal-to-noise ratio (SNR) is proposed for the Si nanowire (Si-NW) biologically-active field-effect transistors (BioFETs). We have fabricated the devices using CMOS compatible process and demonstrated specific alpha fetoprotein (AFP) detection using the monoclonal antibody of AFP. The low-frequency noise was...
Article
The low-frequency noise (LFN) of a p-type nanowire FET (p-NWFET) was characterized and compared with that of an n-type NWFET (n-NWFET) in terms of dominant noise source and its location in the channel region. An inverse proportional dependence of the noise level on channel diameter was observed in the p-NWFET but not in the n-NWFET. The LFN was obs...