• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.32A no.7
• /
• pp.51-57
• /
• 1995

The theoretical analysis for AlInAs/GaInAs resonant tunneling diodes (RTDs), which have shown the improved negative differential resistance (NDR) characteristics, has scarcely been made in comparison with AlGaAS/GaAs RTDs. In this paper, the static current-voltage relation of Al$_{0.48}In_{0.52}As/Ga_{0.47}In_{0.53}$As RTDs were numerically estimated by using a self-consistent method. Assuming a simplified RTD with single quantum well structure and spacer layers, the peak current density (J$_{P}$) and the peak-to-valley current ratio (PVCR) were analysed as the function of the thickness of the well, the barrier and the spacer layer, and temperature. As the results, the peak current density and the peak-to-valley current ratio indicated a reciprocal relation roughly in respect to the thicknesses of the well and the barrier, and it was theoretically predicted that it be not attainable to provide a high peak current desity (J$_{P}$) over 1${\times}10^{5}A/cm^{2}$ as well as the large peak-to-valley current ratio (PVCR) over 10 that were the the critical conditions for the practical use.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.5C no.3
• /
• pp.115-118
• /
• 2005

Currently, molecular devices are reported utilizing active self-assembled monolayers (SAMs) containing the nitro group as the active component, which has active redox centers [1]. SAMs are ordered molecular structures formed by the adsorption of an active surfactant on a solid surface. The molecules will be spontaneously oriented toward the substrate surface and form an energetically favorable ordered layer. During this process, the surface-active head group of the molecule chemically reacts with and chemisorbs onto the substrate In this paper, the electrical properties of the 4'4- di(ethynylphenyl)-2'-nitro-1-benzenethiolate was confirmed. This material is well known as a conducting molecule having possible application to molecular level negative differential resistance (NDR) device. To deposit the self-assembly monolayers onto the gold electrode, the prefabricated Au(1 l l) substrates were immersed into 0.5[mM/l] self-assembly molecule in THF solution. Then, the electrical properties and surface morphologies of 4' 4-di(ethynylphenyl)-2' -nitro-1-benzenethiolate were measured by using the ultra-high vacuum scanning tunneling microscopy (UHV-STM).

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.4
• /
• pp.27-32
• /
• 1997

In resonant tunneling diodes with the quantum well structure showing the negative differential resistance (NDR), it is essential to increase both the peak-to-valley current ratio (PVCR) and the peak current desnity ( $J_{p}$) for the accurate digital switching operation and the high output of the device. In this work, a resonant interband tunneling diode (RITD) with single quantum well structure, which is composed of I $n_{0.47}$As/I $n_{0.52}$A $l_{0.48}$As heterojunction on the InP substrate, is fabricated ot improve PVCR and JP, and then the dependence of I-V charcteristics on the width of the quantum well was investigated.d.ted.d.

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1456-1458
• /
• 1996

In resonant tunneling diodes with the quantum well structure showing the negative differential resistance (NDR), it is essential to increase both the peak-to-valley current ratio (PVCR) and the peak current density ($J_p$) for the accurate switching operation and the high output of the device. In this work, a resonant interband tunneling diode (RITD) with single quantum well structure, which is composed of $In_{0.53}Ga_{0.47}As/ln_{0.52}Al_{0.48}As$ heterojunction on the InP substrate, is suggested to improve the PVCR and $J_p$ through the narrowed tunnel barriers. As the result, the measured I-V curves showed the PVCR over 60.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.51 no.5
• /
• pp.196-198
• /
• 2002

A trench shorted anode LIGBT (TSA-LIGBT) which decreases the device area and the forward voltage drop has been proposed and verified by 2D device simulations. The trench located in the shorted anode would form the shorted anode. The simulation results show that TSA-LIGBT decrease the device area by about 20% and the forward voltage drop by over 75% compared with the conventional ones. Also the troublesome negative differential resistance (NDR) regime has been eliminated successfully in the TSA-LIGBT.

• Proceedings of the KIEE Conference
• /
• 2004.07c
• /
• pp.1715-1717
• /
• 2004

We attempt to investigate morphology of self-assembled dipyridinium dithioacetate on Au(111) substrate by Scanning Tunneling Microscopy(STM). Also, we measured electrical properties using Scanning Tunneling Spectroscopy(STS). Sample that use this experiment acquires thiol function beside quantity by dipyridinium dithioacetate, is structure that can be self-assembled easily to Au(111) substrate. The same self-assembly procedure was used for two different concentrations, 0.5mmol/ml and 1mmol/ml. Dilute density of sample by 0.5mmol/ml, 1mmol/ml and observed dipyridinium dithioacetate's image by STM after self-assembled on Au(111) substrate. The structure of Tip/SAMs/Au(111) has been used measurement for electrical properties(i-v) using STM. The current-voltage measurement result, observed negative differential resistance(NDR) properties.

• Journal of Semiconductor Engineering
• /
• v.1 no.1
• /
• pp.57-63
• /
• 2020

Complementary metal-oxide-semiconductor (CMOS) technology is now facing a power scaling limit to increase integration density. Since 1970s, multi-valued logic (MVL) has been considered as promising alternative to resolve power scaling challenge for increasing information density up to peta-scale level by reducing the system complexity. Over the past several decades, however, a power-scalable and mass-producible MVL technology has been absent so that MVL circuit and system implementation have been delayed. Recently, compact MVL device researches incorporating multiple-switching characteristics in a single device such as 2D heterojunction-based negative-differential resistance (NDR)/transconductance (NDT) devices and quantum-dot/superlattices-based constant intermediate current have been actively performed. Meanwhile, wafer-scale, energy-efficient and variation-tolerant ternary-CMOS (T-CMOS) technology has been demonstrated through commercial foundry. In this review paper, an overview for MVL development history including recent studies will be presented. Then, the status and its future research direction of MVL technology will be discussed focusing on the T-CMOS technology for peta-scale information processing in semiconductor chip.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.05c
• /
• pp.120-123
• /
• 2003

To investigate the characteristics of the single dendrimer molecule, we attempt to measure morphology and electrical properties of the self-assembled dendrimer on Au (111)substrate with SPM(scanning probe microscopy). The same self-assembly procedure was used for two different concentrations, $10{\mu}mol/ml$ and $100{\mu}mol/ml$. The case of lower concentration, we can measure the diameter and the height of the single molecule with the tapping mode AFM image. The imaged single molecules were dome shaped and the average diameter and height were 15.6 nm, 1.2 nm respectively. From these sizes, we can calculate the volume of the single molecule. The volume of the single molecule was estimated about $116nm^3$. However, that of higher concentration, it is difficult to obtain obvious image of the single molecule. To add to, I-V characteristics were investigated using STM, on which the phenomenon of negative differential resistance (NDR)was observed between 0.14 V and 0.24 V reproductively.