• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.41-45
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• 1984

The production of high-quality epitaxial layers almost always involves an etching step of silicon substrates with HCl gas prior to epitaxy, In this work, an investigation has been made on the etch rate and the etch-pit formation as a function of HCl gas concentration and etch temperature at atmospheric pressure (1 atm.) and reduced pressure (0.1 atom.). As a result, it is found that the etch rate is proportional to the square of the HCI gas concentration (XHC12) and the apparent ativation energy is between 0 and 111 Kcal/mole for both ammospheric and reduced pressure operation. From these results, it is expected that the HCI etching of silicon in reduced pressure operation proceeds, as in atmospheric operation, via the reaction ; Si + 2HCl ↔ SiCl2 + H2.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.985-986
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• 2006

The epitaxial $KTa_{0.524}Nb_{0.446}Ti_{0.03}O_3$ films with 3% Ti were investigated. Titanium (+4) substitution on the Nb/Ta site should reduce dielectric losses of KTN: Ti film by introducing an acceptor state. This acceptor state traps electrons due to oxygen vacancies that form during oxide film growth. KTN:Ti films were grown using pulsed laser deposition, and then annealed at different temperatures in oxygen ambient. The crystallinity, and surface morphology of KTN:Ti film were investigated using x-ray diffraction, and atomic force microscopy. The dielectric properties of Ti doped KTN films measured for unannealed and annealed films will be reported. Tunability and dielectric loss of as-deposited KTN:Ti film were determined to be 10% and 0.0134, respectively. For films annealed at $800^{\circ}C$ and $900^{\circ}C$, the dielectric loss decreased but with a decrease in tunability as well.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.3
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• pp.295-298
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• 1999

High quality of $Er_{2}O_{3}$ doped $LiNbO_{3}$ single crystal thin films were grown by the liquid phase epitaxial (LPE) method using $Er_{2}O_{3}$ doped at concentrations of 1,3, and 5 mol% respectively. After the growth of single crystal thin film, the crystallinity and the lattice mismatch along the c-axis between the film and the substrate was examined as a function of the variations of{{{{{Er}_{2}{O}_{3}}}}} dopant concentration using a X-ray double crystal technique. There was no lattice mismatch along the c-axis for the undoped film and those doped with 1 and 3 mol% of $Er_{2}O_{3}$. For 5 mol% of $Er_{2}O_{3}$ doped film, the lattice mismatch was $7.86{\times}10^{-4}$nm along the c-axis.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.3
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• pp.289-294
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• 1999

The charged clusters or particles, which contain hundreds to thousands of atoms or even more, are suggested to from in the gas phase in the thin film processes such as CVD, thermal evaporation, laser ablation, and flame deposition. All of these processes are also phase synthesis of the nanoparticels. Ion-induced or photo-induced nucleation is the main mechanism for the formation of these nanoclusters or nanoparticles in the gas phase. Charge clusters can make a dense film because of its self-organizing characteristics while neutral ones make a porous skeletal structure because of its Brownian coagulation. The charged cluster model can successfully explain the unusual phenomenon of simultaneous deposition and etching taking place in diamond and silicon CVD processes. It also provides a new interpretation on the selective deposition on a conducting material in the CVD process. The epitaxial sticking of the charged clusters on the growing surface is getting difficult as the cluster size increases, resulting in the nanostructure such as cauliflower or granular structures.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.665-668
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• 2001

As reducing the physical size of devices, we can integrate more devices per the unit chip area and make its speed better. We have investigated MOSFET built on an epitaxial layer(EPI) of a heavily-doped ground plane. We compared and analyzed the characteristics of such device structure, i.e., impact ionization, electric field and I-V characteristics curve with lightly-doped drain(LDD) MOSFET. We simulated MOSFET with gate lengths from 0.10 to 0.06${\mu}{\textrm}{m}$ step 0.01${\mu}{\textrm}{m}$ in according to constant voltage scaling theory.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.10
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• pp.828-833
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• 2000

Growth characteristics and microstructure of AIN thin films grown by plasma assisted molecular beam epitaxy on Si substrates have been investigated. Growing temperature and substrate orientation were chosen as major variables of the experiment. Reflection high energy electron diffraction (RHEED), X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy/diffraction (TEM/TED) techniques were employed to characterize the micorstructure of the films. On Si(100) substrates, AlN thin films were grown along the hexagonal c-axis preferred orientation at temperature range 850-90$0^{\circ}C$. However on Si(111), the AlN films were epitaxially grown with directional coherency in AlN(0001)/Si(111), AlN(1100)/Si(110), and AlN(1120)/Si(112) at 85$0^{\circ}C$ and the epitaxial coherencry seemed to be slightly distorted with increasing temperature. The microstructure of AlN thin films on Si(111) substrates showed that the films include a lot of crystal defects and there exist micro-gaps among the columns.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05a
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• pp.30-33
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• 2003

YBCO coated conductor, also called the 2nd generation high temperature superconducting wire, consists of oxide multi-layer hetero-epitaxial thin films. Pulsed laser deposition (PLD) is one of many film deposition methods used to make coated conductor, and is the one known to be the best to make superconducting layer so far. As a part of the effort to make long length coated conductor, the optimum deposition condition of YBCO film on single crystal substrate (SrTiO3) was investigated using PLD. Substrate temperature, oxygen partial pressure, and laser fluence were varied to find the best combination to grow high quality YBCO film.

• ETRI Journal
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• v.13 no.4
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• pp.70-79
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• 1991

$In_1-x$$GA_X$$As_y$$P_1-y$ has a very wide range of applications in optoelectronic devices especially for optical communications because $In_1-x$$GA_X$$As_y$$P_1-y$ has the bandgap of the lowest dispersion ($1.3\mum$) and the lowest loss ( $1.55\mum$) of the optical fiber by changing the composition. The quality of $In_1-x$$GA_X$$As_y$$P_1-y$ epitaxial layer is believed to have a significant effect on the performance of device. The OMVPE growth conditions for the latticematched $In_1x$$GA_X$$As_y$$P_1-y$/InP were investigated. Effects of growth conditions such as V/III ratio, growth temperature, and Ga source material on the electrical and optical properties were studied. The composition, electrical and optical properities of $In_1-x$$GA_X$$As_y$$P_1-y$ were characterized using double crystal X-ray diffractometer (DCD), photoluminescence (PL), XPS(ESCA) and Hall measurement.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1382-1387
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• 2004

From the viewpoint of a macro state, there is no thermal boundary resistance (TBR) at an interface if both surfaces at an interface are perfectly contacted. However, recent molecular dynamics (MD) studies reported that there still exists the TDR at the interface in an ideal epitaxial superlttice. Our previous studies suggested the model to predict the TBR not only quantitatively also qualitatively in superlattices. The suggested model was based on the classical theory of a wave reflection, and provided highly satisfactory results for an engineering purpose. However, it was not the complete model because our previous model was derived by considering only the effects from a mass ratio and a potential ratio of two species. The interaction of two species presented by the Lennard-Jones (L-J) potential is governed by the mutual ratio of the masses, the potential well depths, and the diameters. In this study, we performed the preliminary simulations to investigate the effect resulting from the diameter ratio of two species for the completion of our model and confirmed that it was also a ruling factor to the TBR at an interface in superlattices.

• Journal of the Korean Magnetics Society
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• v.17 no.6
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• pp.246-252
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• 2007

This paper describes the effect of the mixing ratio of starting materials and the growth parameters of magnetic garnet films by LPE on the properties of the films and suggests the conditions to obtain the films suitable for the Faraday rotators of the optical CTs. The properties of the films investigated for the evaluation of the films were thickness, surface morphology, X-ray diffraction, lattice constant, lattice mismatch between film and substrate (single crystal nonmagnetic wafer), and Faraday rotation angle. Optical CTs have been fabricated and evaluated using the films grown.