• 한국진공학회지
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• 제7권s1호
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• pp.15-19
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• 1998

Structural and optical properties of $In_xGa_{1-X}N$ as well as $In_{0.1}Ga_{0.9}N$/GaN single quantum we11 (SQW) grown on sapphire (0001) substrate with an based GaN using rf-plasma assisted MBE have been investigated. The quality of the InXGal.,N fdm was improved as the growth temperature increased. In PL measurements at low temperatures, the band edge emission peaks of $In_xGa_{1-X}N$ was shifted to red region as an indium cell and substrate temperature increased. For $In_{0.1}Ga_{0.9}N$/GaN SQW, the optical emission energy has blue shift about 15meV in PL peak, due to the confined energy level in the well region. And, the FWHM of the $In_{0.1}Ga_{0.9}N$/GaN SQW was larger than that of the bulk Ino,la.9N films. The broadening of FWHM can be explained either as non-uniformity of Indium composition or the potential fluctuation in the well region. Photoconductivity (PC) decay measurement reveals that the optical transition lifetimes of the SQW measured gradually increased with temperatures.

• 한국전기전자재료학회논문지
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• 제18권6호
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• pp.582-586
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• 2005

We have grown GaN layers with in-situ SiN mask by metal organic chemical vapor deposition (MOCVD) and study the physical properties of the GaN layer. We have also investigate the effect of the SiN mask on its optical property. By inserting a SiN mask, (102) the full width at half maximum (FWHM) decreased from 480 arcsec to 409 arcsec and threading dislocation (TD) density decreased from $3.21\times10^9\;cm^{-2}\;to\;9.7\times10^8\;cm^{-2}$. The PL intensity of GaN with SiN mask improved 2 times to that without SiN mask. We have thus shown that the SiN mask improved significantly the physical and optical properties of the GaN layer.

• 한국재료학회지
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• 제18권8호
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• pp.450-453
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• 2008

Mg-doped and In-Mg co-doped p-type GaN epilayers were grown in a low-pressure metal organic chemical vapor deposition technique. The effect of In doping on the p-GaN layer was studied through photoluminescence (PL), persistent photoconductivity (PPC), and transmission electron microscopy (TEM) at room temperature. For the In-doped p-GaN layer, the PL intensity increases significantly and the peak position shifts to 3.2 eV from 2.95 eV of conventional p-GaN. Additionally, In doping greatly reduces the PPC, which was very strong in conventional p-GaN. A reduction in the dislocation density is also evidenced upon In doping in p-GaN according to TEM images. The improved optical properties of the In-doped p-GaN layer are attributed to the high crystalline quality and to the active participation of incorporated Mg atoms.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.18-18
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• 2009

최근 다양하게 연구되고 있는 무분극(nonpolar) 갈륨질화물(GaN) 소재는 자발분극(spontaneous polarization) 및 압전분극(piezoelectric polarization) 등이 발생하지 않아 높은 내부양자효율의 확보가 가능하며, 이러한 장점을 바탕으로 고효율 특성을 갖는 발광다이오드(light-emitting diode) 및 고속 전자소자 등으로의 적용을 위한 연구가 활발히 수행 중 이다. 하지만, 무분극 GaN LED의 구현 시, GaN 박막의 비등방성 성장으로 인한 박막의 막질 저하와 함께 표면에 혼재하는 Ga층과 N층에서 기인되는 절연층의 생성으로 인한 오믹전극 형성의 어려움이 대두되고 있다. 따라서, 고효율의 무분극 GaN LED 구현을 위해서는 무분극 GaN층의 질소층 제거를 위한 표면처리 공정과 더불어 금속/무분극 GaN층 간 발생되는 쇼트키 장벽층의 높이(Schottky barrier height)를 제어하는 연구가 선행되어야 한다. 본 논문에서는 무분극 GaN LED 적용을 위한 n-형 전극물질 및 오믹조건 구현을 위한 금속/무분극 GaN층간 SBH의 제어방법에 대한 연구를 수행하였다.

• 한국표면공학회지
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• 제32권3호
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• pp.416-422
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• 1999

The characteristics of inductively coupled Cl$_2$/BCl$_3$ plasmas during the GaN etching were studied using plasma mass spectrometry by measuring the relative amounts of reactive ions, neutrals, and etch products. GaN etch rates increased with the increase of pressure and showed a maximum near 25mTorr for the pure $Cl_2$ and near 30mTorr for $Cl_2$$BCl_3$. The addition of$ BCl_3$ to $Cl_2$ also was increased GaN etch rates until 50%BCl$_3$ was mixed to $Cl_2$. The GaN etching with pure $Cl Cl_2$ appears to be related to the combination of Cl$_2^{+}$ ion bombardment and the chemical reaction of Cl radicals. In the case of the GaN etching with Cl$_2$/BCl$_3$, in addition to the combined effect of$_2^{ +}$ ions and Cl radicals, $_BCl2^{+ }$ ions appear to be responsible for some of GaN etching even though they do not have significant effect on the GaN etching compared to $Cl_2^{+}$ and Cl. $Ga^{+ }$ , $GaCl^{+}$ , $GaCl_2^{+}$ , and $N_2^{+}$ were observed as the positive ions of etch products, and the intensities of these etch products showed the same trends as those of GaN etch rate. Among the etch products, Ga and $N_2$ appear to be the main etch products.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.237.1-237.1
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• 2011

Resistivity of GaN has been investigated under the influence of ion implantation. n-type, p-type and also undoped GaN has been used here. A ring shape pattern of Au was fabricated on GaN film by the photolithography technique. H, He and Ar were used for implantation. The ion implantation energy, fluence and post-implant annealing temperature varied in this research. Because of the making barrier in some selected area using ions, the resistivity changed in all the samples with the change of both fluence and energy. At room temperature, the resistivity of n-type GaN has been increased from $1.9{\times}10-2$ to $17.7{\times}10-2\;{\Omega}-cm$. This is high for He ion. But undoped and p-type GaN showed some anomalous character.

• 전자공학회논문지 IE
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• 제46권3호
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• pp.1-5
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• 2009

고전력, 고온에서 사용되는 소자에서 RuO2는 다른 전극 물질에 비해 많은 장점을 가지고 있으며, 특히 GaN를 이용하는 소자의 전극물질로서 매우 우수한 특성을 갖음을 확인할 수 있었다. RuO2을 이용한 GaN 소자의 제작은 새로운 전기화학 금속증착법을 통하여 금속배선을 형성하였으며, 과염소산(HClO4)용액을 수용액 사용하였다. RuO2의 두께는 인가전압과 시간에 의존하며, 두께를 조절함으로서 정류성 및 비정류성 소자의 전극으로의 사용 가능성을 확인할 수 있었다.

• Applied Science and Convergence Technology
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• 제26권4호
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• pp.79-85
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• 2017

The crack-free AlGaN template has been successfully grown by using selective area growth with triangular GaN facet. The triangular GaN stripe structure was obtained by vertical growth rate enhanced mode with low growth temperature of $950^{\circ}C$ and high growth pressure of 500 torr. The lateral growth rate enhanced mode of AlGaN for crack-free and flat surface was also investigated. Low pressure of 30 torr and high V/III ratio of 4400 were favorable for lateral growth of AlGaN. It was confirmed that the $4{\mu}m$ -thick $Al_{0.2}Ga_{0.8}N$ was crack-free over entire 2-inch wafer. The dislocation density of $Al_{0.2}Ga_{0.8}N$ was as low as ${\sim}7.6{\times}10^8/cm^2$ measured by cathodoluminescence. Based on the high quality AlGaN with low dislocation density, the ultraviolet laser diode epitaxy with cladding, waveguide and GaN/AlGaN multiple quantum well (MQW) was grown by metalorganic chemical vapor deposition. The stimulated emission at 349 nm with full width at half maximum of 1.8 nm from the MQW was observed through optical pumping experiment with 193 nm KrF laser. We also have fabricated the deep ridge type ultraviolet laser diode (UV-LD) with $5{\mu}m-wide$ and $700{\mu}m-long$ cavity for electrical properties. The turn on voltage was below 5 V and the resistance was ${\sim}55{\Omega}$ at applied voltage of 10 V. The amplified spontaneous emission spectrum of UV-LD was also observed from pulsed current injection.

• 한국재료학회지
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• 제10권10호
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• pp.691-697
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• 2000

자외선 검출소자로 응용될 수 있는 우수한 특성을 지진 $Al_xGa_{1-x}N$ 박막을 MOCVD 법으로 성장시킨 후 박막의 구조적인 특성을 조사하였다. 사파이어 기판 위에 성장된 $Al_xGa_{1-x}N$의 물리적인 특성을 평가하기 위해 Synchrotron Radiation XRD를 사용하였다. $Al_xGa_{1-x}N$의 두께가 커질수록 박막의 결정성은 증가하였으며 아래층은 Undoped GaN의 결정성과 성장된 $Al_xGa_{1-x}N$의 결정성이 서로 비례적인 상관관계를 가지고 있음을 알아내었다. Al 조성비는 막질에 크게 영향을 주었으며 조성비가 높아질수록 표면 형상은 매우 나빠졌다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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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.