Boram Yi's research while affiliated with Sejong University and other places

The performance of ferroelectric field-effect transistor (FeFET)-based ternary content addressable memory (TCAM) is examined to optimize the metal-ferroelectric-metal (MFM) capacitor of FeFET through a compact model based on the multi-domain Preisach theory. To reduce the search delay of the FeFET-based TCAM, the area of the MFM capacitor should be reduced, therefore enhancing polarization. Further, the effect of the polarization properties of ferroelectric material on the performance of the FeFET-based TCAM is explored. The increase in the polarization of ferroelectric material leads to better performance; however, the coercive voltage should also be optimized. As a result, to improve the performance of a circuit using FeFETs, simulations using reliable compact models are required. The results of this study can provide directions for developing ferroelectric materials.

In this study, the bias dependence of low-frequency noise (LFN) in nanowire type gate-all-around (GAA) MOSFETs was physically modeled. In the model, the inversion carrier density distribution was considered based on the potential in the channel that changes according to the bias. The developed model was verified with measurement data of the fabricated device. The model could help circuit designers to optimize noise performance in analog/RF applications when designing integrated circuits using nanowire-type GAA MOSFETs.

Analytical models of low-frequency noise (LFN) characteristics for planar-type tunnel field-effect-transistors (TFETs) are proposed. A surface-potential-based current-voltage model is developed to physically represent the current fluctuation due to charge trapping/detrapping in the gate dielectric. An LFN model can be analytically derived from the current fluctuation with a reasonable approximation. The proposed model is verified using Technology Computer Aided Design (TCAD) and measurement data, which are in good agreement with each other. The analytical model can not only serve as a valuable reference and tool for low-power analog circuit design but also provide physical insights into the LFN of TFETs.

In this study, transient leakage current caused by a parasitic bipolar junction transistor (BJT) in nanowire-type gate-all-around metal–oxide–semiconductor field-effect transistors is physically modeled for circuit design. The model considers the majority carrier concentration in the body, which is modulated by the gate-to-body bias. The parasitic BJT gain is dependent on the majority carrier concentration, which exceeds the body doping concentration in transient conditions. Three-dimensional technology computer-aided design simulation is performed to verify the model. The model accurately predicts the transient leakage current according to various structural parameters.

A physics-based compact model of the parasitic bipolar current induced by an energetic particle is presented for single-event transients in FinFETs. The terminal charges are modeled to predict the body voltage of the FinFET in the transient correctly. The models are implemented using Verilog-A and are verified through three-dimensional technology computer-aided design (TCAD) simulations. The results of the modeling show good agreement with the TCAD data, for both structural variations and energy variations of the energetic particles.

The transient parasitic bipolar effect in floating-body double-gate FinFETs with low-doped bodies is analytically modeled. The obtained analytical transient bipolar current and charge models have predictive power for various device structures. These models are applicable when the majority carrier concentration in accumulation conditions noticeably exceeds the body doping concentration. The physical insights obtained from the developed current model are used to analyze the transient bipolar current I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BJT</sub> (t) for different device structures. It is shown that the gate-body-source capacitive coupling is an important parameter in I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BJT</sub> (t) control.