• Vacuum Magazine
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• v.4 no.4
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• pp.4-13
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• 2017

Quantum structures containing nanoparticles have attracted much attention because of their promising potential applications in electronic and optoelectronic devices operating at lower currents and higher temperatures. The quantum dot is a particle of matter so small that the addition or removal of an electron changes its properties in some useful way. The Quantum dots typically have dimensions measured in nanometers, where one nanometer is 10-9 meter or a millionth of a millimeter. The emission and absorption spectra corresponding to the energy band gap of the quantum dot is governed by quantum confinement principles in an infinite square well potential. The energy band gap increases with a decrease in size of the quantum dot. In this review paper, we will discuss the quantum dot and their application.

• Electronics and Telecommunications Trends
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• v.38 no.1
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• pp.9-16
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• 2023

In the rapidly growing field of quantum computing, it is evident that a robust supply chain is needed for commercialization or large-scale production of quantum chips. As a result, the success of many R&D projects worldwide relies on the development of quantum chip foundries. In this paper, a variety of quantum chip foundries, particularly the ones creating photonic integrated circuit (PIC) quantum chips, are reviewed and summarized to demonstrate current technological trends. Global projects aiming to establish new foundries, as well as information regarding their respective funding, are also included to identify the evolutionary direction of quantum computing infrastructure. Furthermore, the potential application of lithium niobate as a novel material platform for quantum chips is also discussed.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.495-496
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• 2006

• Journal of the Korean Vacuum Society
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• v.15 no.2
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• pp.209-215
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• 2006

We investigated the optical property and the electronic subband structure of InAs quantum dots in an InAsGa/GaAs well structure utilizing photoluminescence (PL), PL excitation (PLE) and near infrared transmission spectroscopy. From transmission and PLE spectra, we found three bound states in the InAs quantum dot and two bound states in InGaAs/GaAs quantum well, and correlated to the results of intersubband transitions observed in photocurrent spectrum.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.3-14
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• 2013

We demonstrate a fashion of quantum channel combining and splitting, called polar quantum channel coding, to generate a quantum bit (qubit) sequence that achieves the symmetric capacity for any given binary input discrete quantum channels. The present capacity is achievable subject to input of arbitrary qubits with equal probability. The polarizing quantum channels can be well-conditioned for quantum error-correction coding, which transmits partially quantum data through some channels at rate one with the symmetric capacity near one but at rate zero through others.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.4
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• pp.278-286
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• 2011

In this paper, we present a compact model of gate-voltage-dependent quantum effects in short-channel surrounding-gate (SG) metal-oxide-semiconductor field-effect transistors (MOSFETs). We based the model on a two-dimensional (2-D) analytical solution of Poisson's equation using cylindrical coordinates. We used the model to investigate the electrostatic potential and current sensitivities of various gate lengths ($L_g$) and radii (R). Schr$\ddot{o}$dinger's equation was solved analytically for a one-dimensional (1-D) quantum well to include quantum effects in the model. The model takes into account quantum effects in the inversion region of the SG MOSFET using a triangular well. We show that the new model is in excellent agreement with the device simulation results in all regions of operation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.591-596
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• 1994

Threshold dependence on stripe width in gain-guided single quantum well lasers has been examined by complex domain effective index method. It is found, in narrow stripe regime, that the lateral optical confinement estimated by newly introduced parameters decreases very rapidly as the transverse optical confinement factor decreases. Thus, in a single quantum well laser with a usually very small, the optical confinement may become very poor depending on stripe width not only in the transverse but also in the lateral direction, further enhancing the gain saturation and often leading to an anomalously high threshold current. The understanding of rather anomalous threshold dependence on stripe width will be very important in optimization of quantum well laser diode structure.

• Korean Journal of Materials Research
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• v.17 no.9
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• pp.489-492
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• 2007

Temperature and injection current dependence of elctroluminescence(EL) spectral intensity of the $In_{0.27}Ga_{0.73}N/GaN$ multi-quantum-well(MQW) have been studied over a wide temperature and as a function of injection current level. EL peaks also show significant broadening into higher photon energy region with the increase of injection current. This is explained by the band-filling effect. When temperature is slightly increased to 300 from 15 K, the EL emission peak showed red-blue-red shift. It can be explained by the carrier localization by potential fluctuation of multiple quantum well and band-gap shrinkage as temperature increase. It is found that a temperature-dependent variation pattern of the EL efficiency under very low and high injection currents show a drastic difference. This unique EL efficiency variation pattern with temperature and current is explained field effects due to the driving forward bias in presence of internal(piezo and spontaneous polarization) fields.

• Journal of Advanced Navigation Technology
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• v.8 no.2
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• pp.91-97
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• 2004

This paper presents the development of InGaAsP multiple quantum well asymmetric Fabry-Perot modulators(AFPM), which have a vertical structure and high performance and describes measurements of devices operating at 10GHz for next generation broadband wireless communication applications such as picocell systems. Advantages of the AFPM include low drive voltage, which is less than -2V, and -3dB coupling loss, good flatness of the frequency response and simple fiber alignment. A simple link demonstration has been introduced, resulting in 92dB/Hz spurious free dynamic range and 40dB inter-modulation distortion. This modulator could be use for broadband radio over fiber systems such as picocell and multiple RF links.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.5
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• pp.716-723
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• 1990

Transmission electron microscopy (TEM) and anger electron microscopy(AES) studies of GaAs/AlxGa1-xAs(x=0.58) quantum wells grown by low pressure metalorganic chemical vapor deposition(LP-MOCVD) are carried out. Isolated quantum well structure having the well width as small as 15 \ulcornerand multiquantum well structure, which consisted of 51 alternating layers with each thickness of 10\ulcorner were suscessfully grown. TEM analyses have shown that their interfaces were almost completely coherent without any structural disorder, alloy clustering and crystal defect. AES depth resolution have shown the compositional periodicity of superlattice structure.