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HVPE 후막 a-plane GaN 결정의 성장과 특성
이충현,황선령,김경화,장근숙,전헌수,안형수,양민,배종성,김석환,장성환,이수민,박길한,Lee, C.H.,Hwang, S.L.,Kim, K.H.,Jang, K.S.,Jeon, H.S.,Ahn, H.S.,Yang, M.,Bae, J.S.,Kim, S.W.,Jang, S.H.,Lee, S.M.,Park, G.H.,Koike, M. 한국결정성장학회 2007 한국결정성장학회지 Vol.17 No.1
본 연구에서는 HVPE(hydride vapor phase epitaxy) 방법으로 r-plane 사파이어 기판 위에 무극성의 (11-20) a-plane GaN을 성장하여 구조적인 특성을 관찰하였다. HVPE 방법으로 저온($500/550/600/660^{\circ}C$)에서 성장한 AIN 버퍼층이 고온의 a-GaN에 미치는 영향을 확인하였다. 또한, AIN 버퍼층과의 비교를 위하여 저온에서 성장한 GaN 버퍼층과 InGaN 버퍼층 같은 다양한 버퍼층을 이용하여 a-plane GaN의 성장도 실시하였다. 고온에서 성장된 a-GaN의 구조적 형상은 저온버퍼층의 성장 조건에 크게 영향을 받음을 알 수 있었다. $GaCl_3$ 전 처리를 실시하고 $820^{\circ}C$에서 성장한 경우에 가장 평탄한 표면을 가지는 a-GaN을 얻을 수 있었다. The structural and morphological properties of planar, nonpolar (11-20) a-plane GaN layers grown by hydride vapor phase epitaxy on (1-102) r-plan sapphire substrates are characterized. We report on the effect of low temperature ($500/550/600/660^{\circ}C$) AIN buffer layers on the structural properties of HVPE grown a-GaN kayers. and for the comparison, low temperature GaN and InGaN buffer layers are also tried for the growth of a-plane GaN layers. The structural geometry of a-GaN layers is severely affected on the growth condition of low temperature buffer layers. The most planar a-GaN could be obtained with $GaCl_3$ pretreatment at the growth temperature of $820^{\circ}C$.
R-plane 사파이어 기판위의 GaN/InGaN 이종접합구조의 HVPE 성장
전헌수,황선령,김경화,장근숙,이충현,양민,안형수,김석환,장성환,이수민,박길한,Jeon, H.S.,Hwang, S.L.,Kim, K.H.,Jang, K.S.,Lee, C.H.,Yang, M.,Ahn, H.S.,Kim, S.W.,Jang, S.H.,Lee, S.M.,Park, G.H.,Koike, M. 한국결정성장학회 2007 한국결정성장학회지 Vol.17 No.1
R-plane 사파이어 위에 a-plane GaN층이 성장된 기판에 혼합소스 HVPE(mixed-source hydride vapor phase epitaxy) 방법으로 GaN/InGaN의 이종접합구조(heterostructure)를 구현하였다. GaN/InGaN 이종접합구조는 GaN, InGaN, Mg-doped GaN 층으로 구성되어 있다. 각 층의 성장온도는 GaN층은 $820^{\circ}C$, InGaN 층은 $850^{\circ}C$, Mg-doped GaN 층은 $1050^{\circ}C$에서 성장하였다. 이때의 $NH_3$와 HCl 가스의 유량은 각각 500 sccm, 10 sccm 이었다. SAG-GaN/InGaN 이종접합구조의 상온 EL (electroluminescence) 특성은 중심파장은 462 nm, 반치폭(FWHM : full width at half maximum) 은 0.67eV 이었다. 이 결과로부터 r-plane 사파이어 기판위에 multi-sliding boat system의 혼합소스 HVPE 방법으로 이종접합구조의 성장이 가능함을 확인하였다. The a-plane GaN layer on r-plane $Al_2O_3$ substrate is grown by mixed-source hydride vapor phase epitaxy (HVPE). The GaN/InGaN heterostructure is performed by selective area growth (SAG) method. The heterostructure consists of a flown over mixed-sourec are used as gallium (or indium) and nitrogen sources. The gas flow rates of HCl and $NH_3$ are maintained at 10 sccm and 500 sccm, respectively. The temperatures of GaN source zone is $650^{\circ}C$. In case of InGaN, the temperature of source zone is $900^{\circ}C$. The grown temperatures of GaN and InGaN layer are $820^{\circ}C\;and\;850^{\circ}C$, respectively. The EL (electroluminescence) peak of GaN/InGaN heterostructure is at nearly 460 nm and the FWHM (full width at half maximum) is 0.67 eV. These results are demonstrated that the heterostructure of III-nitrides on r-plane sapphire can be successfully grown by mixed-source HVPE with multi-sliding boat system.
Se Woon Kim,김동명,이충현,D. W. Kang,김대환,김대정,G.C. Kang,H. T. Kim,이진구,J.U. Lee,K. Y. Kim,K.S. Roh,민경식,이순영,S.H. Seo 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4
We propose a novel photonic base current method to extract the energy-dependent distribution of interface states in heterojunction bipolar transistors (HBTs) by using the photonic current-voltage (I-V) characteristics under sub-bandgap (Eph < Eg) photonic excitation. For the sub-bandgap photonic I-V characterization of HBTs, an optical source with a photon energy less than the bandgap energy of Al0.3Ga0.7As and GaAs (Eph = 0.95 eV < Eg,AlGaAs = 1.79 eV & Eg,GaAs = 1.42 eV) is employed for the characterization of interface states distributed over the photo-responsive energy band (EC .0.95 Eit 0.98 eV) at the emitter-base heterojunction in HBTs by comparing the base currents under a dark condition and sub-bandgap photonic excitation. The trap density at the emitter-base heterojunction interface has been obtained as Dit = 108 1012 eV.1cm.2 over the photo-responsive energy band of AlGaAs/GaAs HBTs under sub-bandgap photonic excitation.
Jay Bok Choi,김동명,이충현,김대환,김대정,D.W. Kang,G.C. Kang,H. T. Kim,이진구,J.U. Lee,K. S. Roh,K. Y. Kim,민경식,S. W. Kim,이순영,S.H. Seo 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.4
In this paper, a novel characterization technique is presented to quantitatively extract the energy distribution of interface states in the gate-to-drain overlapped region of MOSFETs. Optical excitation with a sub-bandgap optical power (Eph = 0.95 eV < Eg,Si = 1.12 eV) is applied over the MOSFETs and the gate-induced drain leakage (GIDL) current, named the optically-induced GIDL, and the energy distribution of interface states in the gate-to-drain overlapped region of MOSFETs can be extracted. The increased drain leakage current under sub-bandgap optical illumination is expected to be predominantly caused by optical trap-assisted tunneling (optical GIDL current, IOTAT = IGIDL = ID,opt . ID,dark). Combining analytical models for the GIDL current, which is increased only by trap-assisted tunneling under sub-bandgap photonic excitation, we extracted interface-state density in the gate-to-drain overlapped region, excluding the band-to-band tunneling current in the off-state drain leakages in MOSFETs. Our optical GIDL current measurement is shown to be in good agreement with the results of the charge pumping and photonic gated diode method (PGDM) results for interface states in MOSFETs. In this paper, a novel characterization technique is presented to quantitatively extract the energy distribution of interface states in the gate-to-drain overlapped region of MOSFETs. Optical excitation with a sub-bandgap optical power (Eph = 0.95 eV < Eg,Si = 1.12 eV) is applied over the MOSFETs and the gate-induced drain leakage (GIDL) current, named the optically-induced GIDL, and the energy distribution of interface states in the gate-to-drain overlapped region of MOSFETs can be extracted. The increased drain leakage current under sub-bandgap optical illumination is expected to be predominantly caused by optical trap-assisted tunneling (optical GIDL current, IOTAT = IGIDL = ID,opt . ID,dark). Combining analytical models for the GIDL current, which is increased only by trap-assisted tunneling under sub-bandgap photonic excitation, we extracted interface-state density in the gate-to-drain overlapped region, excluding the band-to-band tunneling current in the off-state drain leakages in MOSFETs. Our optical GIDL current measurement is shown to be in good agreement with the results of the charge pumping and photonic gated diode method (PGDM) results for interface states in MOSFETs.