초소형 위성 마그네틱토커의 제어 소자에 따른 성능 비교

이주인(Joo-in Lee),박재필(Jae-Pil Park),박기연(Kiyun Park) 한국항공우주학회 2017 한국항공우주학회 학술발표회 논문집 Vol.2017 No.11

NSOM 장치의 제작 및 특성 평가

이주인(Joo In Lee),A. K. Viswanath,유성규(Sungkyu Yu),신정규(Jung-Gyu Shin),유필원(P. W. Yu) 한국진공학회(ASCT) 1999 Applied Science and Convergence Technology Vol.8 No.4(2)

Near-field scanning optical microscope(NSOM) 장치를 자체 제작하고 이의 특성을 조사하였다. 탐침과 시료 사이의 거리 조절을 위해 압전 소자와 He-Ne 레이저를 이용하였으며, 100㎚ 이하의 분해능을 얻을 수 있었다. 이 NSOM 장치를 반도체 분광 연구에 활용하여 GaAs/AlGaAs MQWs와 InAs/GaAs QDs 시료에 대한 photoluminescence, photocurrent 및 reflectance 등의 분광 실험을 수행하였다. PL 실험의 경우 첨예한 광섬유의 끝단을 통과하는 광원의 세기가 매우 약하기 때문에 신호 대 잡음비가 매우 낮았으나 photocurrent 실험에서는 신호 대 잡음비가 100배 이상 좋아짐을 알 수 있었다. 따라서 NSOM을 이용, photocurrent를 측정할 경우 10㎚ 이하의 공간 분해능을 얻을 수 있는 가능성을 보여주었다. We made a near-field optical microscope(NSOM) apparatus and evaluated it. To control the distance between a tip and a sample, we used a piezoelectric translator and a He-Ne laser, and consequently obtained the spatial resolution better than 100 ㎚. For the semiconductor spectroscopic applications, we performed photoluminescence and photocurrent experiments on the GaAs/AlGaAs MQWs samples. In the case of PL experiment, we obtained the low signal to noise ratio due to the extremely small power of a light source passing through the nanometric optical fiber tip. However, photocurrent experiment shows a hundred times better signal to noise ratio than that of PL experiment. This suggests that photocurrent experiment using NSOM have the possibility to provide the spatial resolution better than 10 ㎚.

대면적 레이저 다이오드의 필라멘테이션과 α-factor

한일기,허두창,이정일,이주인,Han, Il-Ki,Her, Du-Chang,Lee, Jung-Il,Lee, Joo-In 한국광학회 2002 한국광학회지 Vol.13 No.4

Linewidth enhancement factor ($\alpha{-factor}$) 값이 2와 4인 두 종류의 1.55${\mu}m$ 다층양자우물(Multi-Quantum Well; MQW) 대면적 레이저 다이오드를 제작하였다. 제작된 레이저 다이오드의 far-field 측정 결과 $\alpha{-factor}$ 값이 4일 때 보다 2인 구조에서 반폭치(Full Width at Half Maximum; FWHM)와 필라멘테이션(filamentation)이 감소되었다. 주입전류의 증가에 따라 두 종류 모두 far-field의 FWHM의 증가 현상이 나타났고 이는 filament spacing이 감소하였기 때문으로 설명된다. 1.55 ${\mu}m$multi-quantum well (MQW) broad area laser diodes with different linewidth enhancement factors ($\alpha{-factor}$) of 2 and 4 were fabricated. The far-fields of the laser diodes were measured. It was observed that the full width at half maximum (FWHM) of the far-fields and the filamentations were reduced in the laser diodes for which the value of the $\alpha{-factor}$ was small. As injection current increased, the FWHM of the far-field also increased regardless of the a-factor. This phenomenon was explained by reduction of filament spacing as injection current increased.

BCl₃ 평판형 유도결합 플라즈마를 이용한 GaAs 건식식각

임완태,백인규,정필구,이제원,조관식,이주인,조국산,Lim, Wan-tea,Baek, In-kyoo,Jung, Pil-gu,Lee, Je-won,Cho, Guan-Sik,Lee, Joo-In,Cho, Kuk-San,Pearton, S.J. 한국재료학회 2003 한국재료학회지 Vol.13 No.4

We studied BCl$_3$ dry etching of GaAs in a planar inductively coupled plasma system. The investigated process parameters were planar ICP source power, chamber pressure, RIE chuck power and gas flow rate. The ICP source power was varied from 0 to 500 W. Chamber pressure, RIE chuck power and gas flow rate were controlled from 5 to 15 mTorr, 0 to 150 W and 10 to 40 sccm, respectively. We found that a process condition at 20 sccm $BCl_3$ 300 W ICP, 100 W RIE and 7.5 mTorr chamber pressure gave an excellent etch result. The etched GaAs feature depicted extremely smooth surface (RMS roughness < 1 nm), vertical sidewall, relatively fast etch rate (> $3000\AA$/min) and good selectivity to a photoresist (> 3 : 1). XPS study indicated a very clean surface of the material after dry etching of GaAs. We also noticed that our planar ICP source was successfully ignited both with and without RIE chuck power, which was generally not the case with a typical cylindrical ICP source, where assistance of RIE chuck power was required for turning on a plasma and maintaining it. It demonstrated that the planar ICP source could be a very versatile tool for advanced dry etching of damage-sensitive compound semiconductors.

수열합성법으로 성장된 ZnO 나노구조의 성장조건에 따른 특성

조민영,김민수,김군식,최현영,전수민,임광국,이동율,김진수,김종수,이주인,임재영,Cho, Min-Young,Kim, Min-Su,Kim, Ghun-Sik,Choi, Hyun-Young,Jeon, Su-Min,Yim, Kwang-Gug,Lee, Dong-Yul,Kim, Jin-Soo,Kim, Jong-Su,Lee, Joo-In,Leem, Jae-Young 한국재료학회 2010 한국재료학회지 Vol.20 No.5

ZnO nanostructures were grown on an Au seed layer by a hydrothermal method. The Au seed layer was deposited by ion sputter on a Si (100) substrate, and then the ZnO nanostructures were grown with different precursor concentrations ranging from 0.01 M to 0.3M at $150^{\circ}C$ and different growth temperatures ranging from $100^{\circ}C$ to $250^{\circ}C$ with 0.3 M of precursor concentration. FE-SEM (field-emission scanning electron microscopy), XRD (X-ray diffraction), and PL (photoluminescence) were carried out to investigate the structural and optical properties of the ZnO nanostructures. The different morphologies are shown with different growth conditions by FE-SEM images. The density of the ZnO nanostructures changed significantly as the growth conditions changed. The density increased as the precursor concentration increased. The ZnO nanostructures are barely grown at $100^{\circ}C$ and the ZnO nanostructure grown at $150^{\circ}C$ has the highest density. The XRD pattern shows the ZnO (100), ZnO (002), ZnO (101) peaks, which indicated the ZnO structure has a wurtzite structure. The higher intensity and lower FWHM (full width at half maximum) of the ZnO peaks were observed at a growth temperature of $150^{\circ}C$, which indicated higher crystal quality. A near band edge emission (NBE) and a deep level emission (DLE) were observed at the PL spectra and the intensity of the DLE increased as the density of the ZnO nanostructures increased.

스핀코팅 방법으로 제작된 ZnO 박막의 두께에 따른 구조적 및 광학적 특성

임광국,김민수,김군식,최현영,전수민,조민영,김형근,이동율,김진수,김종수,이주인,임재영,Yim, Kwang-Gug,Kim, Min-Su,Kim, Ghun-Sik,Choi, Hyun-Young,Jeon, Su-Min,Cho, Min-Young,Kim, Hyeoung-Geun,Lee, Dong-Yul,Kim, Jin-Soo,Kim, Jong-Su,Lee, Joo 한국진공학회 2010 Applied Science and Convergence Technology Vol.19 No.4

스핀코팅 방법으로 제작된 ZnO 박막의 두께에 따른 구조적 및 광학적 특성에 관한 연구를 수행하였다. ZnO 박막의 두께가 두꺼워짐에 따라 줄무늬 모양의 폭과 밀도가 증가하고, 두께가 450 nm 일 때 줄무늬 모양은 사라지며 표면이 매끄러워졌다. ZnO 박막의 표면이 매끄러워졌을 때 orientation factor ${\alpha}_{(002)}$가 급격히 증가하였고, (002) 회절 피크의 FWHM (full width at half maximum)는 감소하였다. ZnO 박막의 NBE (near-band edge emission) 피크의 위치는 두께와 표면 형태의 영향을 거의 받지 않았으나, 매끄러운 표면을 갖는 ZnO 박막의 DLE (deep level emission) 피크의 위치는 청색편이 하였다. ZnO 박막의 두께가 증가함에 따라 DLE 피크에 대한 NBE 피크의 발광세기 비율이 증가하는 경향을 보였고, NBE 피크의 FWHM은 감소하는 경향을 보였다. Thickness effects on the structural and optical properties of ZnO thin films fabricated by spin coating method have been carried out. With increase in the thickness of the ZnO thin films, the width and density of striation shape are increased. The ZnO thin film with thickness of 450 nm has a smooth surface morphology. For the ZnO thin film with a smooth surface, orientation factor ${\alpha}_{(002)}$ is sharply increased and FWHM of (002) diffraction peak is decreased compared to the ZnO thin films with a striation shape surface. Thickness and surface morphology of the ZnO thin films hardly affect the NBE peak position. However, the DLE peak position is blue-shifted as the surface morphology is changed from striation to smooth surface. The PL intensity ratio of the NBE to DLE is increased and the FWHM of NBE peak is decreased as the thickness of the ZnO thin films is increased.

스핀코팅 방법으로 제작된 ZnO 나노 섬유질 박막의 전구체 농도에 따른 표면 및 광학적 특성

김민수,김군식,임광국,조민영,전수민,최현영,이동율,김진수,김종수,이주인,임재영,Kim, Min-Su,Kim, Ghun-Sik,Yim, Kwang-Gug,Cho, Min-Young,Jeon, Su-Min,Choi, Hyun-Young,Lee, Dong-Yul,Kim, Jin-Soo,Kim, Jong-Su,Lee, Joo-In,Leem, Jae-Young 한국진공학회 2010 Applied Science and Convergence Technology Vol.19 No.6

ZnO nano-fibrous thin films with various precursor concentrations ranging from 0.2 to 1.0 mol (M) were grown by spin-coating method and effects of the precursor concentration on surface and optical properties of the ZnO nano-ribrous thin films were investigated by using scanning electron microscopy (SEM) and photoluminescence (PL). ZnO nuclei were formed at the precursor concentration below 0.4 M and the ZnO nano-fibrous thin films were grown at the precursor concentration above 0.6 M. Further increase in the precursor concentration, the thickness of the ZnO nano-fibrous thin films is gradually increased. The intensity and the full-width at half-maximum (FWHM) of the near-band-edge emission (NBE) is increased as the precursor concentration is increased. The deep-level emission (DLE) is red-shifted as the precursor concentration is increased. 스핀코팅 방법을 이용하여 다양한 농도의 전구체로 ZnO 나노 섬유질 박막(ZnO nano-fibrous thin films)을 성장하였고, 그에 따른 표면 및 광학적 특성 변화를 scanning electron microscopy (SEM)와 photoluminescence (PL)을 이용하여 측정하였다. 전구체 농도가 0.4 mol (M) 이하 일 때는 성장률이 낮아 ZnO 핵생성만이 되었고, 0.6 M 이상일 때 ZnO 박막은 나노섬유질 구조가 되었다. 전구체 농도가 더욱 증가함에 따라 ZnO 나노 섬유질의 굵기가 굵어졌고 ZnO 박막의 두께도 단계적으로 두꺼워졌다. 전구체 농도가 증가함에 따라 ZnO 나노 섬유질 박막의 photoluminescence (PL)의 근밴드가장자리 광방출(near-band-edge emission) 피크 세기와 full-width at half-maximu (FWHM)이 증가하였고, 깊은 준위 광방출(deep-level mission) 피크는 적색편이(red-shift)하였다.

수열합성법으로 성장된 ZnO 나노막대의 전구체 농도에 따른 구조적 및 광학적 특성

조민영,김민수,김군식,최현영,전수민,임광국,이동율,김진수,김종수,이주인,임재영,Cho, Min-Young,Kim, Min-Su,Kim, Ghun-Sik,Choi, Hyun-Young,Jeon, Su-Min,Yim, Kwang-Gug,Lee, Dong-Yul,Kim, Jin-Soo,Kim, Jong-Su,Lee, Joo-In,Leem, Jae-Young 한국진공학회 2010 Applied Science and Convergence Technology Vol.19 No.3

수열합성법을 이용하여 전구체 용액 농도에 따라 성장된 ZnO 나노막대의 특성에 대한 연구를 수행하였다. ZnO 씨앗층은 sol-gel법으로 코팅하였고, 그 위에 ZnO 나노막대는 전구체 용액 농도를 0.01 M에서 0.3 M로 변화하여 성장시켰다. FE-SEM (field-emission scanning electron microscopy), XRD (X-ray diffraction), PL (photoluminescence)을 사용하여 ZnO 나노막대의 특성 변화를 분석하였다. 전구체 용액의 농도가 증가함에 따라 ZnO 나노막대의 직경과 길이가 증가하였으며 광학적 특성이 향상되었다. ZnO nanorods were grown on ZnO seed layer by hydrothermal method. The ZnO seed layer was coated by sol-gel method, and then the ZnO nanorods on ZnO seed layer were grown with different precursor concentrations ranging from 0.01 M to 0.3 M. FE-SEM (field-emission scanning electron microscopy), XRD (X-ray diffraction), and PL (photoluminescence) were employed to investigate the structural and optical properties of the ZnO nanorods. The diameter and length of ZnO nanorods are increased and also the optical properties are enhanced as the precursor concentrations are increased.

수열합성법으로 성장된 산화아연 나노막대의 특성 및 열처리 효과

전수민,김민수,김군식,조민영,최현영,임광국,김형근,이동율,김진수,김종수,이주인,임재영,Jeon, Su-Min,Kim, Min-Su,Kim, Ghun-Sik,Cho, Min-Young,Choi, Hyun-Young,Yim, Kwang-Gug,Kim, Hyeoung-Geun,Lee, Dong-Yul,Kim, Jin-Soo,Kim, Jong-Su,Lee, Joo 한국진공학회 2010 Applied Science and Convergence Technology Vol.19 No.4

수열합성법으로 실리콘 (111) 기판 위에 산화아연 나노막대를 성장하였다. 산화아연 나노막대를 성장하기 전, 실리콘 기판에 스핀코팅법으로 씨앗층을 성장하였다. 산화아연 나노막대는 오토클레이브(autoclave)로 $140^{\circ}C$에서 6시간 동안 성장하였고, 아르곤 분위기에서 300, 500, $700^{\circ}C$의 온도로 20분 동안 열처리하였다. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL)를 이용하여 열처리한 산화아연 나노막대의 구조적, 광학적 특성을 분석하였다. 모든 산화아연 나노막대 시료에서 c-축 배향성을 나타내는 강한 ZnO (002) 회절 피크와 약한 ZnO (004) 회절 피크가 나타났다. 열처리 온도가 증가함에 따라 산화아연 나노로드의 residual stress는 compressive에서 tensile로 변하였다. Hexagonal 형태의 산화아연 나노로드를 관찰하였다. 산화아연 나노로드의 PL 스펙트럼은 free-exciton recombination에 의해 3.2 eV에서 좁은 near-band-edge emission (NBE) 피크와 산화아연 나노막대의 결함에 의해 2.12~1.96 eV에서 넓은 deep-level emission (DLE) 피크가 나타났다. 산화아연 나노막대를 열처리함에 따라, NBE 피크의 세기는 감소하였고 DLE 피크는 열처리에 의해 발생한 산소 관련 결함에 의하여 적색편이 하였다. Vertically aligned ZnO nanorods on Si (111) substrate were prepared by hydrothermal method. The ZnO nanorods on spin-coated seed layer were synthesized at $140^{\circ}C$ for 6 hours in autoclave and were thermally annealed in argon atmosphere for 20 minutes at temperature of 300, 500, $700^{\circ}C$. The effects of the thermal annealing on the structural and optical properties of the grown on ZnO nanorods were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL). All the ZnO nanorods show a strong ZnO (002) and weak (004) diffraction peak, indicating c-axis preferred orientation. The residual stress of the ZnO nanorods is changed from compressive to tensile by increasing annealing temperature. The hexagonal shaped ZnO nanorods are observed. The PL spectra of the ZnO nanorods show a sharp near-band-edge emission (NBE) at 3.2 eV, which is generated by the free-exciton recombination and a broad deep-level emission (DLE) at about 2.12~1.96 eV, which is caused by the defects in the ZnO nanorods. The intensity of the NBE peak is decreased and the DLE peak is red-shifted due to oxygen-related defects by thermal annealing.