• Title/Summary/Keyword: AlN crystal

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Growth and Properties of GaN by Vapor Transport Epitaxy (Vapor Transport Epitaxy에 의한 GaN의 성장과 특성)

  • Lee, Jae-Bum;Kim, Seon-Tai
    • Korean Journal of Materials Research
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    • v.16 no.8
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    • pp.479-484
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    • 2006
  • Highly c-axis oriented poly-crystalline GaN with a dimension of $1{\sim}3\;{\mu}m$ was deposited on $c-Al_2O_3$ substrate by vapor transport epitaxy (VTE) method at the temperature range of $900{\sim}1150^{\circ}C$. XRD intensities from (00'2) plane of grown GaNs were increased with reaction conditions which indicate the improvement of the crystal quality. In the PL spectra measured at 10 K, the spectrum composed with the neutral-donor bound exciton-related emission at 3.47 eV, crystal defect-related emission band at 3.42 eV and with its phonon replicas. The fact that intensity of $I_2$ were increased and FWHM were decreased with growth conditions means that the quality of GaN crystals were improved. With this simple VTE technology, we confirm that the GaNs were simply deposited on sapphire substrate and crystal quality related to optical properties of GaN grown by VTE were relatively good. PL emission without deep level emission in spite of polycrystalline structure can be applicable to the fabrication of large area and low cost optical devices using poly-GaN grown by VTE.

Sintering phenomena and grain growth of ultra-fine spinel$(MgAl_2O_4)$; (I) (초미분 spinel$(MgAl_2O_4)$ 의 입성장 및 소결 현상 (I))

  • 이형복;한영환
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.9 no.1
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    • pp.43-49
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    • 1999
  • In the paper, Significant sintering phenomena at refractory temperature ranges, from $1400^{\circ}C$ to $1700^{\circ}C$, of the pure spinel ($MgAl_{2}O_{4}$) and the experimental data from other researchers are analysed and compared in terms of density ($\rho$), grain growth exponent(n), and activation energy (Q). Similar to the density rewsults, the grain growth results above $1600^{\circ}C$ appear similar for the spinel, but for temperatures lower than about $1600^{\circ}C$ results are distinctly differently grouped. However, the grain growth exponents are different, six for the spinel (below $1600^{\circ}C$), and five at high temperatures(above $1600^{\circ}C$), with the activation energy of 474$\pm$38 kJ/mol below $1600^{\circ}C$, which is very close to the published values, 360~580 kJ/mol.

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Electrical Properties of V-I Curve of p-ZnO:Al/n-ZnO:Al Junction Fabricate by RF Magnetron Sputtering

  • Jin, Hu-Jie;So, Soon-Jin;Song, Min-Jong;Park, Choon-Bae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.408-409
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    • 2007
  • Al-doped p-type ZnO films were fabricated on n-Si (100) and homo-buffer layers in pure oxygen at $450^{\circ}C$ by RF magnetron sputtering. Target was ZnO ceramic mixed with 2wt% $Al_2O_3$. XRD spectra show that the Al-doped ZnO thin films have ZnO crystal structure and homo-buffer layers are beneficial to Al-doped ZnO films to grow along c-axis. Hall Effect experiments with Van der Pauw configuration show that p-type carrier concentrations are ranged from $1.66{\times}10^{16}\;to\;4.04{\times}10^{18}cm^{-3}$, mobilities from 0.194 to $2.3cm^2V^{-1}s^{-1}$ and resistivities from 7.97 to $18.4{\Omega}cm$. P-type sample has density of $5.40cm^{-3}$ which is smaller than theoretically calculated value of $5.67cm^{-3}$. XPS spectra show that O1s has O-O and Zn-O structures and A12p has only Al-O structure. P-ZnO:Al/n-ZnO:Al junctions were fabricated by magnetron sputtering. V-I curves show that the p-n junctions have rectifying characteristics.

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Gallium Nitride Epitaxy films Growth with Lower Defect Density (결함밀도가 낮은 Gallium Nitride Epitaxy 막 제조)

  • 황진수
    • Korean Journal of Crystallography
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    • v.9 no.2
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    • pp.131-137
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    • 1998
  • 결정결함의 밀도가 낮은 GaN epitaxy 막을 MOCVD(metal organic chemical vapour deposition) 방법에 의해 성장시켰다. 기판은 6H-SiC를 사용하였으며, AlN과 GaN으로 구성된 이중 buffer 층을 도입하였다. GaN buffer 층은 반응원료인 trimethyl gallium(TMG)과 NH3 가스를 교호식펄스공급(alternating pulsative supply, APS)방법에 의해 만들었다. AlN buffer/6H-SiC 위에 초기단계에 형성되는 GaN 섬은 APS처리에 의해 크기가 커지는 것을 AFM(atomic force microscope)으로 관찰하였다. Buffer 층의 역할은 그 위에 성막시킨 GaN epitaxy 막의 결정성과 결함밀도에 의해 조사하였다. 성막된 GaN의 결정구조와 결정성은 DCXRD(double crystal X-ray diffractormeter)에 의해 측정되었다. 결정결함은 EPD(etching pit density)를 측정하는 방법으로 알칼리혼합용에서 처리된 막을 SEM(scanning electron microscope)으로 관찰하였다.

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The characteristics of AlN buffered GaN on ion beam modified Si(111) substrates (Si(111) 위에 Ion beam 처리 후 AlN layer를 완충층으로 이용하여 성장시킨 GaN의 특성)

  • Kwang, Min-Gu;Chin, Jeong-Geun;Lee, Jae-Seok;Oh, Seung-Seok;Hyun, Jin;Byun, Dong-Jin
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.03a
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    • pp.99-99
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    • 2003
  • The growth of GaN on Si is of great interest due to the several advantages : low cost, large size and high-quality wafer availability as well as its matured technology. The crystal quality of GaN is known to be much influenced by the surface pretreatment of Si substrate[1]. In this work, the properties of GaN overlayer grown on ion beam modified Si(111) have been investigated. Si(111) surface was treated RIB with 1KeV-N$_2$$\^$+/(at 1.9 ${\times}$ 10$\^$-5/) to dose ranging from 5${\times}$10$\^$15/ to 1${\times}$10$\^$17/ prior to film growth. GaN epilayers were grown at 1100$^{\circ}C$ for 1 hour after growing AlN buffer layers for 5∼30 minutes at 1100$^{\circ}C$ in Metal Organic Chemical Vapor Deposition (MOCVD). The properties of GaN epilayers were evaluated by X-Ray Diffraction(XRD), Raman spectroscopy, Photoluminescence(PL) and Hall measurement. The results showed that the ion modified treatment markedly affected to the structural, optical and electrical characteristic of GaN layers.

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The characteristics of AlN buffered GaN on ion implanted Si(111) (이온주입된 Si(111)에 AlN 완충층을 이용하여 성장시킨 GaN 박막의 특성)

  • 강민구;진정근;이재석;노대호;양재웅;변동진
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.11a
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    • pp.165-165
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    • 2003
  • The growth of GaN on Si is of great interest due to the several advantages low cost, large size and high-quality wafer availability as well as its matured technology. The crystal quality of GaN is known to be much influenced by the surface pretreatment of Si substrate [1]. In this work, the properties of GaN overlayer grown on ion implanted Si(111)and bare Si(111) have been investigated. Si(111) surface was treated ion implantation with 60KeV and dose 1${\times}$10$\^$16//$\textrm{cm}^2$ prior to film growth. GaN epilayers were grown at 1100$^{\circ}C$ for 1 hour after growing AlN buffer layers for 15-30 minutes at 1100$^{\circ}C$ with metal organic chemical vapor deposition (MOCVD). The properties of GaN epilayers were evaluated by X-Ray Diffraction (XRD), Scanning electron microscope (SEM) Photoluminescence (PL) at room temperature and Hall measurement The results showed that the GaN on ion implanted Si(111) markedly affected to the structural, optical and electrical characteristic of GaN layers.

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Growth and optical characteristics of the non-phosphor white LED by mixed-source HVPE (혼합소스 HVPE에 의한 비형광체 백색 LED의 성장과 광 특성)

  • Kim, E.J.;Jeon, H.S.;Hong, S.H.;Han, Y.H.;Lee, A.R.;Kim, K.H.;Ha, H.;Yang, M.;Ahn, H.S.;Hwang, S.L.;Cho, C.R.;Kim, S.W.
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.19 no.2
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    • pp.61-65
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    • 2009
  • In this paper, we report on the growth and optical characteristics of white-LED without fluorescent material. The growth of DH(double heterostructure) with AlGaN active layer was performed on a n-GaN/(0001) $Al_{2}O_{3}$ by the mixed-source HVPE and multi-sliding boat. The CRI(color rendering index) of packaging device charged in the range 72-93 with CIE chromaticity coordinates(x=$0.26{\sim}0.34$, y=$0.31{\sim}0.40$). And CCT(correlated color temperature) values was measured $5126{\sim}10406K$ with increasing injection current. The CIE point of conventional phosphor white LED shifts blue region, but cm point of non-phosphor white LED shifts opposite direction. These results show the mixed-source HVPE can be possible to newly fabricate method of phosphor free white LED with high CRI value.

Homoepitaxial Growth on GaN Substrate Grown by HVPE (HVPE법에 의해 성장된 GaN 기판의 Homoepitaxial 성장)

  • Kim, Chong-Don;Kim, Young-Soo;Ko, Jung-Eun;Kwon, So-Young;Lee, Sung-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.14-14
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    • 2006
  • Homoepitaxial growth of GaN on n-type GaN substrates was carried out by hydride vapor phase epitaxy (HVPE) method. This enables us to reduce or to eliminate the bowing of the GaN substrate caused by thermal mismatch. As a result, the two opposite crystal surfaces have been found to possess low dislocation density. The surface polarity of the homoepitaxially grown GaN was confirmed by both etching of the surface and conversion beam electron diffraction(CBED). The surface morphology and the photoluminescencemeasurement indicated that the surface properties of N-polar face of the homoepitaxlally grown GaN are quite different from the initial N-polar face of the heteroepitaxially grown GaN substrate Also, both surfaces of the GaN substrate were characterized by room temperature Double crystal X-ray diffraction (DCXRD) and photoluminescence measurement.

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Single-crystal Structure of Fully Dehydrated and Largely NH4+-exchanged Zeolite Y (FAU, Si/Al = 1.70), │(NH4)60Na11│[Si121Al71O384]-FAU

  • Seo, Sung-Man;Kim, Ghyung-Hwa;Kim, Young-Hun;Wang, Lian-Zhou;Lu, Gao-Qing;Lim, Woo-Taik
    • Bulletin of the Korean Chemical Society
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    • v.30 no.3
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    • pp.543-550
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    • 2009
  • The single-crystal structure of largely ammonium-exchanged zeolite Y dehydrated at room temperature (293 K) and 1 ${\times}\;10^{-6}$ Torr. has been determined using synchrotron X-radiation in the cubic space group $Fd\overline{3}m\;(a=24.9639(2)\AA)$ at 294 K. The structure was refined to the final error index $R_1$ = 0.0429 with 926 reflections where $F_o>4\sigma(F_o)$; the composition (best integers) was identified as |$(NH_4)_{60}Na_{11}$|[$Si_{121}Al_{71}O_{384}$]-FAU. The 11 $Na^{+}$ ions per unit cell were found at three different crystallographic sites and 60 ${NH_4}^{+}$ ions were distributed over three sites. The 3 $Na^{+}$ ions were located at site I, the center of the hexagonal prism ($Na-O\;=\;2.842(5)\;\AA\;and\;O-Na-O\;=\;85.98(12)^{\circ}$). The 4 $Na^{+}$ and 22 ${NH_4}^{+}$ ions were found at site I' in the sodalite cavity opposite the double 6-rings, respectively ($Na-O\;=\;2.53(13)\;\AA,\;O-Na-O\;=\;99.9(7)^{\circ},\;N-O\;=\;2.762(11)\;\AA,\;and\;O-N-O =\;89.1(5)^{\circ}$). About 4 $Na^{+}$ ions occupied site II ($(Na-O\;=\;2.40(4)\;\AA\;and\;O-Na-O\;=\;108.9(3)^{\circ}$) and 29 ${NH_4}^{+}$ ions occupy site II ($N-O\;=\;2.824(9)\;\AA\;and\;O-N-O\;=\;87.3(3)^{\circ}$) opposite to the single 6-rings in the supercage. The remaining 9 ${NH_4}^{+}$ ions were distributed over site III' ($N-O\;=\;2.55(3),\;2.725(13)\;\AA\;and\;O-N-O\;=\;94.1(13),\;62.16(15),\;155.7(14)^{\circ}$).

Optical and Structural Properties of GaN Grown on AlN/Si via Molecular Beam Epitaxy Using Ammonia (암모니아를 이용하여 분자선에피탁시 방법으로 AIN/Si 기판에 성장시킨 GaN의 구조적,광학적 특성)

  • Kim, Gyeong-Hyeon;Hong, Seong-Ui;Gang, Seok-Jun;Lee, Sang-Hyeon;Kim, Chang-Su;Kim, Do-Jin;Han, Gi-Pyeong;Baek, Mun-Cheol
    • Korean Journal of Materials Research
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    • v.12 no.5
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    • pp.387-390
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    • 2002
  • A new approach of using double buffer layers of AlN and GaN for growth of GaN films on Si has been undertaken via molecular beam epitaxy using ammonia. The first buffers layer of AlN was grown using $N_2$plasma and the second of GaN was grown using ammonia. The surface roughness of the grown films was investigated by atomic force microscope and was compared with the normally grown films on sapphire. Double crystal x-ray rocking curve and low temperature photoluminescence techniques were employed for structural and optical properties examination. Donor bound exciton peak at 3.481 eV with full width half maximum of 41 meV was observed at 13K.