Chemical Beam Epitaxial Growth of InP and GaP by Using Tertiarybutylbis (Dimethylamino) Phosphine

류혁현,Cho-Rong Kim,Gerald Stringfellow,Jaeyeop Lee,Jae-Young Leem,Laurence Sadwick 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.III

We report the growth of indium phosphide (InP) by using a chemical beam epitaxy (CBE) technique with the group V source tertiarybutylbis (dimethylamino) phosphine (TBBDMAP). The photoluminescence spectra at 15 K showed that the intensity of a peak attributed to impurity recombination and the FWHM increased significantly when the cracker temperature exceed 545 $^\circ$C. This paper also reports the growth of GaP without precracking of the TBBDMAP source. While it was not possible to grow InP at 450 $^\circ$C, GaP was successfully grown at temperatures as low as 410 $^\circ$C, possibly due to the higher Ga-P bond strength which gives a longer TBBDMAP residence time on the surface before desorption. In this study, ethyldimethylindium (EDMIn) and triisopropylgallium (TlPGa) were used as the indium (In) and the gallium (Ga) sources, respectively.

수열합성 법으로 성장된 산화 아연 나노로드의 전구체 농도에 따른 구조적, 광학적 특성 연구

류혁현,Ryu, H. 한국진공학회 2009 Applied Science and Convergence Technology Vol.18 No.1

본 연구에서는 metal oxide chemical vapor deposition (MOCVD)을 이용하여 p형 실리콘(100) 기판 위에 30 nm 두께의 산화 아연 완충층을 $500^{\circ}C$ 에서 증착 시킨 후, 그 위에 산화 아연 나노로드를 수열합성법을 이용하여 성장시켰다. 그리고 산화아연 나노로드 성장 시 0.02몰${\sim}$0.5몰의 다양한 농도의 전구체를 사용함으로써 그에 따라 변화되는 산화 아연 나노로드의 배열상태, 구조적, 그리고 광학적 특성 평가를 실시하였다. 특성 평가는 FE-SEM(field emission scanning electron microscopy), XRD(X-ray diffraction), 그리고 PL(photoluminescence) 등의 분석 방법들을 통해 이루어졌다 본 연구를 통하여 전구체의 농도가 증가할수록 나노로드의 직경과 길이가 길어지며 0.3몰의 농도에서 뛰어난 광학 특성이 나타나는 것을 발견할 수 있었다. Zinc Oxide (ZnO) nanorods arrays were deposited on ZnO buffered p-Si(100) substrates by hydrothermal method. The ZnO buffer layer with a thickness of 30 nm was deposited by metal oxide chemical vapor deposition at $500^{\circ}C$. The structural and optical properties of ZnO nanorods arrays controlled by precursor concentrations from 0.06 to 0.5 M were studied by FE-SEM(field emission scanning electron microscopy), XRD(X-ray diffraction), and PL(photoluminescence), respectively. It was found that the structural and optical properties of ZnO nanorods arrays are changed significantly with increase of precursor concentration. The sizes of diameter and length of nanorods were increased as the concentration increase, and good optical property was shown with the concentration of 0.3 M.

Improvement of CuO photostability with the help of a BiVO4 capping layer by preventing self-reduction of CuO to Cu2O

정현진,류혁현,배종성 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.104 No.-

We fabricated BiVO4/CuO heterojunction photoelectrodes by depositing BiVO4 capping layers on CuOphotoelectrodes and investigated the photocurrent density and photostability of the photoelectrodesaccording to the number of BiVO4 depositions using the spin coating method. The morphological, structural,optical, electrical and photoelectrochemical properties of the BiVO4/CuO photoelectrode wereinvestigated using field-emission scanning electron microscopy, X-ray diffraction (XRD), X-ray photoelectronspectroscopy (XPS), UV–visible spectroscopy, electrochemical impedance spectroscopy, and threeelectrodepotentiostat/galvanostat equipment. XRD and XPS results showed that the crystallinities andbinding energies of BiVO4/CuO photoelectrodes were affected by BiVO4 compared to the CuO photoelectrode. In particular, XPS measurements showed that the Cu 2p3/2 peak binding energies of the CuO photoelectrodeand BiVO4/CuO photoelectrodes with poor photostabilities shifted to those of Cu2O, showingself-reduction from CuO to Cu2O, after photostability measurement. In contrast, BiVO4/CuO photoelectrodeswith proper BiVO4 deposition cycles showed good photostabilities without self-reduction. TheBiVO4/CuO photoelectrode with 4 BiVO4 deposition cycles showed a high photostability of 76.2% via photocorrosionsuppression, which is a much improved result compared to the single CuO photoelectrodewith a photostability of 13.1%. However, the photocurrent density of 1.77 mA/cm2 (vs. SCE at0.55 V) is still low, and further study is necessary.

A Systematic Study of the Relationship among the Morphological, Structural and Photoelectrochemical Properties of ZnO Nanorods Grown Using the Microwave Chemical Bath Deposition Method

오성진,류혁현,이원재 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.3

In this study, zinc oxide (ZnO) nanostructures were grown on a ZnO seed layer/fluorine-doped tin oxide (FTO) substrate for different growth durations ranging from 5 to 40 min using the microwave chemical bath deposition method. We studied the effect of growth duration on the morphological, structural, optical and photoelectrochemical properties of the ZnO nanostructures. From this study, we found that the photoelectrochemical properties of the ZnO nanostructures were largely affected by their morphological and structural properties. As a result, we obtained the highest photocurrent density of 0.46 mA/cm2 (at 1.5 V vs. SCE) from the sample grown for 30 min.

버퍼막 두께에 따른 ZnO/ZnO/p-Si(111) 이종접합 다이오드 특성 평가

허주회,류혁현,이종훈,Heo, Joo-Hoe,Ryu, Hyuk-Hyun,Lee, Jong-Hoon 한국재료학회 2011 한국재료학회지 Vol.21 No.1

In this study, the effects of an annealed buffer layer with different thickness on heterojunction diodes based on the ZnO/ZnO/p-Si(111) systems were reported. The effects of an annealed buffer layer with different thickness on the structural, optical, and electrical properties of zinc oxide (ZnO) films on p-Si(111) were also studied. Before zinc oxide (ZnO) deposition, different thicknesses of ZnO buffer layer, 10 nm, 30 nm, 50 nm and 70 nm, were grown on p-Si(111) substrates using a radio-frequency sputtering system; samples were subsequently annealed at $700^{\circ}C$ for 10 minutes in $N_2$ in a horizontal thermal furnace. Zinc oxide (ZnO) films with a width of 280nm were also deposited using a radio-frequency sputtering system on the annealed ZnO/p-Si (111) substrates at room temperature; samples were subsequently annealed at $700^{\circ}C$ for 30 minutes in $N_2$. In this experiment, the structural and optical properties of ZnO thin films were studied by XRD (X-ray diffraction), and room temperature PL (photoluminescence) measurements, respectively. Current-voltage (I-V) characteristics were measured with a semiconductor parameter analyzer. The thermal tensile stress was found to decrease with increasing buffer layer thickness. Among the ZnO/ZnO/p-Si(111) diodes fabricated in this study, the sample that was formed with the condition of a 50 nm thick ZnO buffer layer showed a strong c-axis preferred orientation and I-V characteristics suitable for a heterojunction diode.

Photoelectrochemical properties of Fe2O3 nanorods grown with an Na2SO4 additive

최하영,류혁현,이원재 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.63 No.-

Fe2O3 photoelectrodes were grown using a microwave chemical bath deposition (MW-CBD) method with an Na2SO4 additive at various concentrations. We investigated the effects of the Na2SO4 additive concentration on the morphological, optical, structural, electrical, and photoelectrochemical properties of the Fe2O3 photoelectrodes using scanning electron microscopy, ultraviolet-visible spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy and potentiostat/galvanostat measurements, respectively. The Na2SO4 concentration was found to affect the properties of the Fe2O3 photoelectrodes, including the photoelectrochemical properties. Consequently, the highest photocurrent density value of 0.39 mA/cm2 was obtained from the sample prepared with an Na2SO4 concentration of 0.03 M.

마이크로파 화학 용액 증착법을 이용하여 성장시킨 ZnO 나노로드의 형태학적, 구조적, 광학적 그리고 광전기화학적 특성 변화 연구

오성진,류혁현,이원재 대한금속·재료학회 2017 대한금속·재료학회지 Vol.55 No.4

In this study, zinc oxide (ZnO) nanostructures were grown on a ZnO-buffered fluorine-doped tin oxide (FTO) substrate using a microwave chemical bath deposition method with different zinc oxide precursor concentrations from 0.01 to 0.5 M. We investigated the effects of the zinc oxide precursor concentration on the morphological, structural, optical and photoelectrochemical properties of the ZnO nanostructures. From this work, we found that ZnO one-dimensional structures mainly grew along the (002) plane, and the nanorod length, diameter, surface area and photoelectrochemical properties were largely dependent on the precursor concentration. That is, the photoelectrochemical properties were affected by the morphological and structural properties of the ZnO. The morphological, structural, optical and photoelectrochemical properties of the ZnO nanostructure were investigated by field emission scanning electron microscopy (FE-SEM) and atomic force microscope (AFM), X-ray diffraction (XRD), UV-visible spectroscopy and 3-electrode potentiostat. We obtained the highest photocurrent density of 0.37 mA/cm2 (at 1.1 V vs. SCE) from the precursor concentration of 0.07 M, which resulted in ZnO nanostructures with proper length and diameter, large surface area and good structural properties.

Effect of O2 plasma pretreatment on structural and optical properties of ZnO films on PES substrate by atomic layer deposition

허주회,류혁현,이원재 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5

ZnO films were deposited on the O2 plasma treated polyethersulfone (PES) substrates by atomic layer deposition. X-ray diffraction (XRD) measurements reveals that the grains in ZnO films show strongly (0 0 2) preferential orientation, when the duration of plasma pretreatment increases. The decreased grain size and improved crystallinity results in the decreased surface roughness of ZnO films. In contrast,when the duration of plasma pretreatment increases to 60 min, the surface roughness increases again due to the increased grain size and worse crystallinity. In photoluminescence measurement, slight blue shift of near-band-edge emission occurs with increasing duration of plasma pretreatment up to 30 min.

버퍼막 두께 및 버퍼막 열처리 온도에 따른 ZnO/b-ZnO/p-Si(111)의 전기적 특성 변화 및 이종접합 다이오드 특성 평가

허주회,류혁현,Heo, Joo-Hoe,Ryu, Hyuk-Hyun 한국진공학회 2011 Applied Science and Convergence Technology Vol.20 No.1

본 논문에서는 버퍼막 두께 및 열처리 온도에 따른 ZnO/b-ZnO/p-Si(111) 기반 이종접합 다이오드 전류 특성에 대한 연구가 진행되었고, b-ZnO (ZnO buffer layer) 버퍼막 두께 및 열처리 온도에 따른 p-Si(111) 기판 위에 증착시킨 ZnO 박막의 구조적, 전기적 특성 또한 연구되었다. X-ray diffraction (XRD) 방법을 이용하여 ZnO 박막의 구조적 특성을 측정하였고, semiconductor parameter analyzer를 이용하여 ZnO/b-ZnO/p-Si(111) 이종접합 다이오드의 I-V 특성을 평가하였다. XRD 분석 결과 버퍼막 열처리 온도 $700^{\circ}C$, 버퍼막 두께 70 nm에서 ZnO 박막은 우세한 (002) 방향의 c-축 배향성을 갖는 육방정계(hexagonal wurtize) 결정 구조를 나타내었다. 전기적 특성인 운반자 농도, 비저항 값의 경우에는 버퍼막 열처리 온도 $700^{\circ}C$, 버퍼막 두께 50 nm에서 우수한 전기적 특성(비저항: $2.58{\times}10^{-4}[{\Omega}-cm]$, 운반자 농도: $1.16{\times}10^{20}[cm^{-3}]$)을 보였다. 또한 ZnO/b-ZnO/p-Si(111) 이종접합 다이오드의 전류 특성은 버퍼막 열처리 온도 $700^{\circ}C$에서 버퍼막 두께가 증가할수록 전류 특성이 향상되는 경향을 보였다. In this study, the effects of ZnO buffer layer thickness and annealing temperature on the heterojunction diode, ZnO/b-ZnO/p-Si(111), were reported. The effects of those on the structural and electrical properties of zinc oxide (ZnO) films on ZnO buffered p-Si (111) substrate were also studied. Structural properties of ZnO thin films were studied by X-ray diffraction and I-V characteristics were measured by a semiconductor parameter analyzer. ZnO thin films with 70 nm thick buffer layer and annealing temperature of $700^{\circ}C$ showed the best c-axis preferred orientation. The best electrical property was found at the condition of buffer layer annealing temperature of $700^{\circ}C$ and 50nm thick ZnO buffer layer (resistivity: $2.58{\times}10^{-4}[{\Omega}-cm]$, carrier concentration: $1.16{\times}1020[cm^{-3}]$). The I-V characteristics for ZnO/b-ZnO/p-Si(111) heterojunction diode were improved with increasing buffer layer thickness at buffer layer annealing temperature of $700^{\circ}C$.

수열합성법으로 성장된 산화 아연 나노로드의 성장 온도에 따른 구조적, 광학적 특성 연구

정용일,류혁현,Jeong, Yong-Il,Ryu, Hyuk-Hyun 한국진공학회 2011 Applied Science and Convergence Technology Vol.20 No.3

본 연구에서는 수열합성법으로 성장시킨 정렬된 산화아연 나노로드의 성장온도에 따른 구조적, 광학적 특성이 조사되었다. Zinc nitrate ($Zn(NO_3)_2$)와 hexamethylenetetramine가 전구체로 사용되었으며 40 nm 두께의 산화아연 버퍼막이 증착된 실리콘 (100) 기판이 사용되었다. 산화아연 나노로드는 $55^{\circ}C$에서 $115^{\circ}C$까지의 성장 온도에서 40 nm 산화아연 버퍼레이어 위에 성장되었다. 결과 분석을 위하여 FE-SEM, XRD, PL 방법 등이 사용되었다. 분석 결과, 잘 정렬된 산화아연 나노로드가 모든 샘플에서 관찰되었다. $95^{\circ}C$ 이하의 증착 온도에서 성장된 산화아연 나노로드의 끝부분은 평평하였으며, $115^{\circ}C$의 증착 온도에서 성장된 산화아연 나노로드의 끝부분은 날카로운 바늘모양의 형태를 나타내었다. 또한 $115^{\circ}C$의 증착 온도에서 비평형 성장때문에 엉킨 나노 구조물이 부분적으로 생성되었다. 성장 온도는 산화아연의 구조적, 광학적 특성에 영향을 미칠 수 있다. 구조적 특성의 경우 성장 온도가 $75^{\circ}C$까지 증가함에 따라 XRD (002) 피크 세기가 증가했고, 성장온도가 $115^{\circ}C$까지 계속적으로 증가함에 따라 피크의 크기는 다시 감소하였다. 광학적 특성에서는, 성장 온도가 증가함에 따라 가시광선 영역 피크 세기에 대한 UV 피크 세기 비율이 증가하였고, $95^{\circ}C$의 성장온도에서는 가장 큰 UV 피크의 세기를 얻을 수 있었다. In this study, the effects of growth temperature on structural and optical properties of hydrothermally grown ZnO nanorod arrays have been investigated. Zinc nitrate ($Zn(NO_3)_2$) and hexamethylenetetramine were used as precursors. The ZnO buffered Si(100) with a thickness of 40 nm was used as the substrates. The ZnO nanorods were grown on these substrates with the temperature ranging from 55 to $115^{\circ}C$. The results were characterized by scanning electron microscope, X-ray diffraction and room temperature photoluminescence measurements. Well-aligned ZnO nanorods arrays were obtained from all samples. The tips of nanorods were flat when the temperature was less than $95^{\circ}C$, and the sharp-tip nanoneedle-like morphologies were obtained with the temperature of $115^{\circ}C$. In addition, some bundles were on the nanorods arrays with $115^{\circ}C$ due to the non-equilibrium growth. The growth temperature could affect the crystal and optical properties of ZnO. For the effects on crystal properties, the intensity of (002) peak was increased as the temperature was increased to $75^{\circ}C$, then decreased as the temperature was further increased to $115^{\circ}C$. As for the effects on optical properties, the intensity ratio of UV peak to visible peak is increased with the temperature increasing and the strongest UV peak intensity was obtained with the growth temperature of $95^{\circ}C$.