• Journal of the Korean Vacuum Society
• /
• v.2 no.4
• /
• pp.501-506
• /
• 1993

The spatial potential distribution of electron cyclotron resonance plasma is measured as a function of tehsubstrate DC bias by Langmuir probe method. It is observed that the substrate DC bias changes the slope of the plasma potential near the subsrate, resulting in changes in flux and energy of the impinging ions across plasma $_strate boundary along themagnetric field. The effect of the substrate DC bias on the low-temperature silicon homoepitaxy (below $560^{\circ}C$) is examine dby in situ reflection high energy electron diffraction (RHEED), cross-section transmission electron microscopy (XTEM),plan-view TEM and high resolution transmision electron microscopy(HRTEM). While the polycrystalline silicon layers are grow withnegative substrate biases, the single crystaline silicon layers are grown with negative substrate biases, the singel crystalline silicon layers are grown with positive substrate biases. As the substrate bias changes form negative to positive values, the growth rate decreases. It is concluded that the control of the ion energy during plasma deposition is very important in silicon epitaxy at low temperatures below $560^{\circ}C$ by UHV-ECRCVD.VD.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.8
• /
• pp.15-23
• /
• 1998

Single crystalline I $n_{x}$G $a_{1-x}$ N thin film was grwon by MOCVD on (001) sapphire substrate for the blue light emitting devices. A good quality of I $n_{0.13}$G $a_{0.87}$N/GaN heterostructure grwon above 700.deg. C was confiremed by various characterization techniques of AFM, RHEED and DC-XRD. Through PL measurement at room temperautre for the Si-Zn co-doped I $n_{x}$G $a_{a-x}$N/GaN structure grwon at 800.deg. C to obtain blue wavelength emission, 460-470 nm and 425 nm emission peak were observed, which are believed to be from donor-to-acceptor pair transition and band edge emission of In/x/G $a_{1-x}$ N, respectively. The result of PL measurement of the undoped MQW I $n_{x}$G $a_{1-x}$ N layer at low temperature confirmed that the strong MQW peak was resulted by exciton from the GAN barrier and carrier of DA pair confined into the well layer.ll layer.yer.r.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.6
• /
• pp.446-450
• /
• 2013

Growth mechanism of GS-MBE(Gas source-Molecular Beam Epitaxy) has been investigated. We observed that the growth rate of GaN films is changing from 520 nm/h to 440 nm/h by the variation of V/III ratio under nitrogen-rich growth condition. It was explained that the amount of hydrogen on the growth front varies by the ammonia flow, and gallium hydrides are generated on the surface by a reaction of hydrogen and gallium, resultantly the amount of gallium supplying is changing along with the $NH_3$ flow. Reflection high energy electron diffraction (RHEED) observation was used to confirm the N-rich condition. The crystal quality of GaN was estimated by photoluminescence (PL) and X-ray diffraction (XRD).

• Journal of the Korean Vacuum Society
• /
• v.5 no.2
• /
• pp.133-138
• /
• 1996

Epitaxial cubic silicon carbide films have been deposited on carbonized Si(001) substrates using the single precursor 1, 3-disilabutane in the temperature range 900-$1000^{\circ}C$ under high vacuum conditions. The films grown were characterized by in situ RHEED, XPS, XRD, x-ray pole figure, SEM, and TEM. The results show that epitaxial cubic SiC films with smooth morphology and good crystallinity were formed in this temperature range. The single precursor 1, 3-disilabutane has been found suitable for the epitaxial growth of cubic SiC on Si(001) substrates.

• Applied Science and Convergence Technology
• /
• v.26 no.3
• /
• pp.52-54
• /
• 2017

An InGaN/GaN multiple quantum well (MQW) structure is grown on a GaN/sapphire template using a plasma-assisted molecular beam epitaxy (PA-MBE). The fluctuation of the quantum well thickness formed from roughly-grown InGaN layer results in a disordered photoluminescence (PL) spectrum. The surface morphologies of the InGaN layers with various In compositions are investigated by reflection high energy electron diffraction (RHEED) and atomic force microscopy (AFM). A blurred InGaN/GaN hetero-interface and the non-uniform QW size is confirmed by high resolution transmission electron microscopy (HR-TEM). Inhomogeneity of the quantum confinement results in a degradation of the quantum efficiency even though the InGaN layer has a uniform In composition.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2009.12a
• /
• pp.190-190
• /
• 2009

We report the epitaxial growth of MgO and CoFe/MgO on Ge (001) substrates using molecular beam epitaxy. It was found that the epitaxial growth of a MgO film on Ge could be realized at a low growth temperature of $125{\pm}5^{\circ}C$ and the MgO matches the Ge with a cell ratio of $\sqrt{2}$:1 which renders MgO rotated by $45^{\circ}$ relative to Ge. In-situ and ex-situ structural characterizations reveal the epitaxial crystal growth of bcc CoFe/MgO on Ge with the in-plane crystallographic relationship of CoFe(001)[100] || MgO(001)[110] || Ge(001)[100], exhibiting sharp interfaces in the (001) matching planes. The saturation magnetization of the sample is $1430{\pm}20$ emu/cc, which is comparable to the value of bulk CoFe.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07b
• /
• pp.1010-1014
• /
• 2004

High quality GaN layer and $In_xGa_{1-x}N$ alloy were obtained on (0001)sapphire substrate using ammonia$(NH_3)$ and dimethylhydrazine$(DMH_y)$ as a nitrogen source by gas source molecular hem epitaxy(GSMBE) respectively. As a result, RHEED is used to investigate the relaxation processes which take place during the growth of GaN and $In_xGa_{1-x}N$. The full Width at half maximum of the x-ray diffraction(FWHM) rocking curve measured from Plane of GaN has exhibitted as narrow as 8 arcmin. Photoluminescence measurement of GaN and $In_xGa_{1-x}N$ were investigated at room temperature, where the intensity of the band edge emission is much stronger than that of deep level emission. In content of $In_xGa_{1-x}N$ epitaxial layer according to growth condition was investigated.

• Journal of the Korean institute of surface engineering
• /
• v.29 no.6
• /
• pp.753-759
• /
• 1996

The artificial construction of well-defined low-dimensional (low-D) quantum structures, such as quantum wire (QWR) still attracts attention of many researchers due to their applications in room-temperature optoelectronic devices. In this work, the migration enhanced epitaxial growth (MEE) and the analysis of InAs/ AlAs QWR are reported. On the vicinal semi-insulating InP substrate of $3^o$ tilted cut from (100) surface towards (010) direction, InAs/ AlAs QWR superlattices have been successfully grown by MEE with the introduction of growth interruption at each shutter operation of MBE cell. The in-situ RHEED analyses show that MEE gives superior step-flow growth (SFG) and sharper interface formation over a conventional MBE growth. We have grown 4 samples in series varying the growth temperature. The QWR samples are analyzed by photoluminescence (PL) and atomic force microscopy (AFM). From the AFM images, we can get the definitely resolved 1-D structures. This structure is believed to be due to the MEE method and its separation is better than any other data from others. We are now studying the dependence of the structure on the growth temperature.

• Journal of Korean Vacuum Science & Technology
• /
• v.1 no.1
• /
• pp.38-44
• /
• 1997

Epitaxial growth of SiC films on Si(111) substrates without carbonization was carried out n the temperature range of 900-100$0^{\circ}C$ under high vacuum conditions by single source chemical vapor deposition (CVD) of 1,3-disilabutane (H$_3$SiCH$_2$SiH$_2$$CH_3$). The monocrystalline nature of the films was confirmed by XRD, RHEED and cross-sectional TED. Cross-sectional TEM image indicated that no void exists and the boundary is clear and smooth at the SiC-Si(111) interface. RBS and AES analyses also showed that the films are stoichiometric and homogeneous in depth, From the results, this single source growth techniqe of using 1,3-disilabutane has been found suitable and effective for epitaxial growth of stoichiometric SiC on Si(111) without carbonization at temperatures below 100$0^{\circ}C$.

• Korean Journal of Materials Research
• /
• v.5 no.3
• /
• pp.297-309
• /
• 1995

본 연구에서는 이온선보조증착법에 의해 Si(100)기판위에 정합성장된 $Si_{0.5}$Ge_{0.5}$층의 핵성성과 성장을 고찰하였다. 성장층에 대한 AFM(Atomic Force Microscopy), RHEED(Reflection High Energy Electron diffraction) 등의 분석결과 Si(100)기판위에 이온선보조증착에 의하여 성장된 $Si_{0.5}$Ge_{0.5}$층은 Stranski-Kranstanov(SK)기구로 성장되며, 300eV, 10 $\mu$A/$cm^{2}$의 Ar이온선을 조사시키는 경우 결정성이 향상되었고, SK 성장 방식의 임계두께가 증가하였다. Ar 이온선 조사에 의해 MBE에 의한 정합성장온도(55$0^{\circ}C$-$600^{\circ}C$)보다 훨씬 낮은 20$0^{\circ}C$에서 정합성장이 가능하였으며, $x_{mn}$값은 10.5%로 MBE에 의한 정합성장시 보고된 $x_{mn}$ 값보다 낮았다. 이온충돌에 의해 발생한 3차원 island의 분해와 표면확산의 증가가 $Si_{0.5}$Ge_{0.5}$층의 성장에 현저한 영향을 미쳤으며, 이온충돌의 영향은 3차원 island의 생성보다 3차원 island의 분해가 더 안정한 낮은 증착온도에서만 관찰되었다.