Hojoon Lee

Dr. Hojoon Lee


Research Focus & Metrics

Academic Career Length

34Years (1993-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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19 August 2019 in IEEE Sensors Journal
Verified
Journal Article
Closed access
CPChanoh Park
Chanoh Park
WCWonyeong Choi
Wonyeong Choi
DKDonghoon Kim
Donghoon Kim
BJBo Jin
Bo Jin
HLHojoon Lee
Hojoon Lee
Highly sensitive silicon-nanonet biologically active field-effect transistors (BioFETs) for the detection of influenza A (H1N1) virus have been demonstrated using a top-down process. The BioFETs show excellent intrinsic electrical characteristics, such as a low threshold voltage of 0.7 V and high on/off current ratio of ∼107. The sensing characteristics were measured at room temperature with various concentrations of H1N1 virus in a range of 10 pg/ml -100 ng/ml. The current-related sensitivity (SI) shows a higher value in the subthreshold regime, where SI is strongly correlated with the subthreshold swing (SS). The voltage-related sensitivity (SV) shows almost constant behavior from the subthreshold regime to the linear regime. The limit of detection (LOD) was 10 pg/ml, which is 6 times lower than values previously reported for FET-type sensors. In addition, the nanonet sensors exhibit high specificity to influenza A virus with negligible false positive for influenza B virus.

1 September 2002 in Applied Optics
Verified
Journal Article
Closed access
PDF file
HLHojoon Lee
Hojoon Lee
We propose and demonstrate experimentally a multiple fiber Bragg grating sensor system that uses a LED as a light source and adapts the code-division multiple access method to separate individual sensor signals. We measured static and dynamic strains and cross-talk levels among sensor signals. With our proposed scheme, a low-cost sensor system can be designed with a fast response speed. Cross-talk levels between sensor signals are found to be below the -30-dB level.

2 February 2024 in Sensors
Verified
Journal Article
Open access
PDF file
HSHyun Chul Sagong
Hyun Chul Sagong
SJSeongcheol Jeong
Seongcheol Jeong
HLHojoon Lee
Hojoon Lee
Hydrogen fuel cell vehicles have gained more attention as future automobiles due to their environmental benefits and extended driving ranges. Concurrently, the global hydrogen sensor market is also experiencing substantial growth. These sensors are integrated into vehicles to detect hydrogen leakage and concentration, thereby ensuring the safety of hydrogen fuel cell vehicles. In particular, hydrogen pressure sensors, commonly installed on the manifold and regulator of vehicles, can measure hydrogen pressure and diagnose safety concerns caused by hydrogen leakage in advance. In this paper, we identify the vulnerable points of hydrogen pressure sensors when exposed to vehicle driving environments, investigate failure mechanisms, and provide process optimization techniques. Specifically, our reliability modeling verifies that the components of a printed circuit board (PCB) exposed to humid environments undergo corrosion due to ion migration, leading to the generation of extrinsic series or parallel resistances, which in turn cause fluctuations of output voltage. Through structural and elemental analysis, we pinpoint process-related factors that make components vulnerable to humidity, thereby suggesting recommendations for enhancing the manufacturing process. Based on this analysis in the development stage, we can proactively address and improve reliability and further safety-related issues for future automobiles, thus preventing real field issues.

16 October 2024 in IEEE Access
Verified
Journal Article
Open access
MSMinki Suh
Minki Suh
MRMinsang Ryu
Minsang Ryu
JHJonghyeon Ha
Jonghyeon Ha
MBMinji Bang
Minji Bang
DLDabok Lee
Dabok Lee
JKJungsik Kim
Jungsik Kim
This study investigates the row hammer tolerance and potential degradation by capacitive crosstalk (CC) and parasitic bipolar junction transistor (BJT) effect in vertically stacked dynamic random-access memory (VS-DRAM) using technology computer-aided design (TCAD) simulations. The close arrangement of word lines in VS-DRAM results in a subthreshold leakage by the CC effect. Furthermore, as VS-DRAM has a floating body, hole accumulation in the body occurs via gate-induced drain leakage (GIDL) at the storage node in the cell that stores ‘1’. This can be accelerated by activating the bit line (BL). This causes leakage current ( IBJT ) by the parasitic BJT when the BL state becomes low and it is found that IBJT can be enhanced by the CC effect in this study. The row hammer effect and IBJT by the CC and parasitic BJT effects can be mitigated by reducing Si width.

7 December 2016 in IEEE Electron Device Letters
Verified
Journal Article
Closed access
HLHojoon Lee
Hojoon Lee
JLJunyoung Lee
Junyoung Lee
SBSangwon Baek
Sangwon Baek
WJWoong Hee Jeong
Woong Hee Jeong
YLYongsu Lee
Yongsu Lee
HLHojoon Lee
Hojoon Lee
This letter presents the electrical characteristics of newly proposed network-channel low-temperature polysilicon channel (LTPS) thin-film transistors (TFTs). Due to effective reduction of grain boundary traps and enhanced gate controllability, the network-channel TFTs show better subthreshold slope, lower threshold voltage, and higher ON- OFF current ratio, compared with conventional planar devices. The extracted grain boundary trap density and the interface trap density are significantly reduced in the network-channel devices. In addition, the network-channel devices show higher immunity to hot-carrier stressing, which are confirmed from the low-frequency noise characteristics with various stressing time. These results suggest that the network-channel devices are very promising for next-generation LTPS TFT applications.

11 September 2024 in IEEE Access
Verified
Journal Article
Open access
MBMinji Bang
Minji Bang
JHJonghyeon Ha
Jonghyeon Ha
MSMinki Suh
Minki Suh
DLDabok Lee
Dabok Lee
MRMinsang Ryu
Minsang Ryu
JKJungsik Kim
Jungsik Kim
The effects of single event upset (SEU) by alpha particles and heavy ions on the data flip of a 3 nm technology node gate-all-around (GAA) nanosheet field-effect transistor (NSFET) 6T static random access memory (SRAM) cell was studied through technology computer-aided design (TCAD) simulations. It was found that the sensitivity to radiation in the “off” pull-down transistor varies depending on the position of the alpha particle and heavy ions in the incident. The most significant radiation-induced increase in electron density occurs at the drain–channel junction. Heavy ion strikes lead to the lowest threshold linear energy transfer ( LETth ) value during the hold operation compared to read and write operations. The partial bottom dielectric isolation (PDI) scheme demonstrates lower radiation sensitivity than the conventional scheme, as the PDI layer acts as a physical barrier preventing charge migration from the substrate to the drain.