Kasidit Toprasertpong 교수

The comparatively high coercive field in Hf_0.5Zr_0.5O₂ (HZO) and other HfO₂-based ferroelectric thin films leads to two critical challenges for their application in embedded ferroelectric memory: high operating voltage due to a large thickness-field product and poor endurance due to the high operating field close to the breakdown field. In this study, we demonstrate that the thickness scaling of ferroelectric HZO down to 4 nm is a promising approach to

A quasi-static split C-V technique is proposed as a novel method to monitor ferroelectric polarization and charge distribution in FeFETs. In contrast to conventional split C-V, which is not applicable to FeFETs, the proposed technique successfully detects charges induced by V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> at the ferroelectric-semiconductor interfaces and extracts real P-V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML"

Crystallization annealing is a key process for the formation of the ferroelectric phase in HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based ferroelectric thin films. In this study, we systematically investigate the notable tradeoff of the annealing process, with temperature varied from 300°C to 700°C, on the Hf <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> Zr <sub xmlns:mml

Abstract Reservoir computing offers efficient processing of time-series data with exceptionally low training cost for real-time computing in edge devices where energy and hardware resources are limited. Here, we report reservoir computing hardware based on a ferroelectric field-effect transistor (FeFET) consisting of silicon and ferroelectric hafnium zirconium oxide. The rich dynamics originating from the ferroelectric polarization dynamics and polarization-charge coupling are the keys leading t

A memory window (MW) of ferroelectric field-effect transistors (FeFETs), defined as a separation of the HIGH-state and the LOW-state threshold voltages, is an important measure of the FeFET memory characteristics. In this study, we theoretically investigate the relation between the FeFET MW and the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="ht

Abstract Bandgap engineering of strain‐balanced InGaAs/GaAsP multiple quantum wells (MQWs) allows high‐quality materials with an absorption edge beyond GaAs to be epitaxially grown in Ge/GaAs‐based multijunction solar cells. We demonstrate MQW solar cells with effective bandgaps ranging from 1.31 eV to as low as 1.15 eV. The bandgap‐voltage‐offset of MQWs is found to be independent of effective bandgaps and superior to a bulk reference by approximately 0.1 V. This implies the merit of high photo

We have investigated the device operation of Si ferroelectric FETs (FeFET) through direct measurements of polarization and electron/hole densities in p-FeFETs and n-FeFETs. Unlike electrons in n-FeFETs, inversion holes in p-FeFETs are found to be well coupled with ferroelectric polarization, resulting in inversion hole density N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> enhanced up to 2.5×10 <sup xmlns:mml="http://www.w3.org/1998/Math/

Tunneling enhancement of cell performance in InGaAs/GaAsP multiple quantum well (MQW) solar cells has been studied to investigate the potential in overcoming the carrier collection problem, which hinders the maximum performance of quantum structure solar cells. To accurately investigate the effects of the tunneling effect, the study was carried out in samples with different GaAsP barrier thickness, controlled absorption edge, and constant built-in field. The tunneling effect has been confirmed b

We investigate a theoretical model for effective carrier mobility to comprehensively describe the behavior of the perpendicular carrier transport across multiple quantum well (MQW) structures under applied electric field. The analytical expressions of effective mobilities for thermionic emission, direct tunneling, and thermally assisted tunneling are derived based on the quasithermal equilibrium approximation and the semiclassical approach. Effective electron and hole mobilities in InGaAs/GaAsP

Co-designing materials, devices, and the operating scheme, we demonstrate a 2T memory gain cell based on ITO, with excellent properties: 1) zero-volt standby with long retention $(\sim 8\mathrm{s}$ extrapolated for 1 fF storage); 2) operating voltage of 1.9 V with sufficient write current for sub-ns write, owing to good ITO mobility (here $\gt20$ cm$^{2} /\mathrm{V}/\mathrm{s}$); 3) write and read schemes with current-sensing that fully recover the potential drop from wordline capacitive couplin

Understanding of transport dynamics of both electrons and holes in quantum-structure solar cells is essential for their structure design and performance enhancement. By applying our proposed carrier time-of-flight technique on p-on-n and n-on-p configurations, we can separately evaluate electron and hole transport across quantum structures inserted in the i-region of solar cells. Electron and hole behaviors in two sets of InGaAs/GaAsP multiple-quantum-well (MQW) solar cells with different potent

Carrier transport across multiple quantum well (MQW) structures inserted in the i-region of a p-i-n diode is an important mechanism that determines the performance of MQW solar cells. We have employed a carrier time-of-flight measurement technique using a quantum-well probe to investigate the electron transport time across MQW structures. Delay of the carrier arrival time, defined as time-of-flight, caused by MQWs shows almost linear increment to the number of wells. Tunneling transport in InGaA

Breakdown is one of main failure mechanisms that limit write endurance of ferroelectric devices using hafnium oxide-based ferroelectric materials. In this study, we investigate the gate current and breakdown characteristics of Hf 0.5 Zr 0.5 O 2 /Si ferroelectric field-effect transistors (FeFETs) by using carrier separation measurements to analyze electron and hole leakage currents during time-dependent dielectric breakdown (TDDB) tests. Rapidly increasing substrate hole currents and stress-induc