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Plasma로 활성화된 질소 원자를 사용한 사파이어 기판 표면의 저온 질화처리의 XPS 연구
이지면(Ji-Myon Lee),백종식(Jong-Sik Paek),김경국(Kyonng-Kook Kim),김동준(Dong-Joon Kim),김효근(Hyo-Gun Kim),박성주(Seong-Ju Park) 한국진공학회(ASCT) 1998 Applied Science and Convergence Technology Vol.7 No.4
원격 플라즈마 화학기상증착법(Remote Plasma Enhanced-Ultrahigh Vacuum Chemical Vapor Deposition)에 의해 활성화된 질소 원자를 사용하여 사파이어 기판의 표면을 저온에서 질화처리한 후 표면의 화학적 조성을 조사하였다. 질화처리에 의해 주로 표면에 형성된 물질은 AlN임을 X-선 광전자 분광방법(X-ray photoelectron spectroscopy: XPS)을 사용하여 확인하였다. 또한 플라즈마의 RF 출력, 반응 온도 및 시간에 따라서 기판의 Al과 반응한 질소의 상대적인 양과, 표면 형태를 XPS와 AFM(atomic force microscopy)을 사용하여 조사하였다. 플라즈마에 의해서 활성화되어 기판과 반응한 질소의 양은 RF 출력에 따라 증가하지만 Al과 반응하여 AlN을 형성시킨 질소는 RF 출력에 따라 증가한 후 일정하게 됨을 관찰하였다. 그러나 질화 처리 온도와 시간의 증가에 따른 AlN의 상대적인 양은 비교적 무관함을 관찰하였다. 또한 Ar 스퍼터링을 통한 XPS의 depth profile을 관찰한 결과 질화층은 깊이에 따라 3개의 다른 층으로 이루어져 있음을 확인하였다. The chemical aspects of nitridated surface of sapphire(0001) have been studied by X-ray photoelectron spectroscopy. Nitridated layer was formed by remote plasma enhanced-ultrahigh vacuum deposition at a low temperature range. It was confirmed that this nitridated surface was mainly consists of AlN layer. The relative amounts of nitrogen reacted with Al on the sapphire surface and their surface morphology were investigated with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) as a function of radio-frequency power, reaction temperature, and reaction time. The amounts of atomic nitrogen activated by plasma which was subsequently incorporated into sapphire were increased with RF power. But the amounts of nitrogen reacted with Al in sapphire was initially increased and then remained constant. However, the relative amounts of AlN were nearly constant with irrespective of nitridation temperature and time. Furthermore, a depth profile of nitridated layer with XPS showed that the nitridated surface consisted of three layers with different stoichiometry.
InP/InGaAsP 광자결정 구조 제작을 위한 건식 식각 특성
이지면,Lee, Ji-Myon 한국전기전자재료학회 2004 전기전자재료학회논문지 Vol.17 No.12
Two-dimensionally arrayed nanocolumn lattices were fabricated by using double-exposure laser holographic method. The hexagonal lattice was formed by rotating the sample with 60 degree while the square lattice by 90 degree before the second laser-exposure. The reactive ion etching for a typical time of 30 min using CH$_4$/H$_2$ plasma enhanced the aspect-ratio by more than 1.5 with a slight increase of the bottom width of columns. The etch-damage was observed by photoluminescence (PL) spectroscopy which was removed by the wet chemical etching using HBr/$H_2O$$_2$/$H_2O$ solution, leading into the enhanced PL intensities of the PCs.
투명전자소자를 위한 HfO<sub>2</sub>계 투명 MIM 커패시터 특성연구
조영제,이지면,곽준섭,Jo, Young-Je,Lee, Ji-Myon,Kwak, Joon-Seop 한국진공학회 2009 Applied Science and Convergence Technology Vol.18 No.1
The effects of $HfO_2$ film thickness on electrical, optical, and structural properties were investigated. We fabricated ITO/$HfO_2$/ITO metal-insulator- metal (MIM) capacitor using transparent conducting oxide. When $HfO_2$ film thickness increase from 50 nm to 300 nm, dielectric constant of $HfO_2$ was decreased from 20.87 to 9.72. The transparent capacitor shows an overall high performance, such as a dielectric constant about 21 by measuring the ITO/$HfO_2$/ITO capacitor structures and a low leakage current of $2.75{\times}10^{-12}\;A/cm^2$ at +5 V. Transmittance above 80% was observed in visible region. 투명 전자소자의 고유전 $HfO_2$ 절연막을 개발하기 위하여, ITO/$HfO_2$/ITO 금속-절연체-금속 (Metal-Insulator-Metal, MIM) 커패시터 구조를 형성한후 $HfO_2$ 박막의 두께에 따른 전기적, 광학적, 구조적 특성의 변화를 연구하였다. $HfO_2$ 박막의 두께가 50 nm에서 300 nm로 증가함에 따라 유전상수는 20에서 10이하로 감소하였으나, $HfO_2$ 두께가 증가함에 따라 누설전류는 감소하여 200 nm 이상의 두께에서는 $2.7{\times}10^{-12}\;A/cm^2$ 이하의 낮은 누설전류 특성을 나타내었다. ITO/$HfO_2$/ITO MIM 커패시터의 $HfO_2$ 박막의 두께가 50 nm에서 300 nm로 증가함에 따라 투과율은 감소하였으나 300 nm 두께에서도 가시광선 영역에서 80% 이상의 투과율을 나타내어 우수한 투과도 특성을 나타내었다.
Dewetting된 Pt Islands를 Etch Mask로 사용한 GaN 나노구조 제작
김택승,이지면,Kim, Taek-Seung,Lee, Ji-Myon 한국재료학회 2006 한국재료학회지 Vol.16 No.3
A method for fabrication of nano-scale GaN structure by inductively coupled plasma etching is proposed, exploiting a thermal dewetting of Pt thin film as an etch mask. The nano-scale Pt metal islands were formed by the dewetting of 2-dimensional film on $SiO_2$ dielectric materials during rapid thermal annealing process. For the case of 30 nm thick Pt films, pattern formation and dewetting was initiated at temperatures greater $600^{\circ}C$. Controlling the annealing temperature and time as well as the thickness of the Pt metal film affected the size and density of Pt islands. The activation energy for the formation of Pt metal island was calculated to be 23.2 KJ/mole. The islands show good resistance to dry etching by a $CF_4$ based plasma for dielectric etching indicating that the metal islands produced by dewetting are suitable for use as an etch mask in the fabrication of nano-scale structures.
오정훈,이지면,Oh, Jung-Hoon,Lee, Ji-Myon 한국재료학회 2006 한국재료학회지 Vol.16 No.1
The characteristics of the wet-etching of ZnO thin films were investigated using hydrochloric and phosphoric acid solutions as etchants. The etch rate of ZnO films, using highly diluted hydrochloric acid solutions at a concentration of 0.25% in deionized water, was determined to be about 120 nm/min, and linearly increased with increasing the acid concentration, resulting in $1.17{\mu}m/min$ when a 2% HCl solution was used. The surface of ZnO etched by an HCl solution, observed by scanning electron microscopy, showed a rough morphology with a high density of hexagonal pyramids or cones with sidewall angles of about ${\sim}45^{\circ}C$. Moreover, the sidewall angles of the masked area were similar to those of the pyramids on the surface. In comparison, the surface of ZnO etched by a phosphoric acid had a smooth surface morphology. The origin of this difference is from the very initial stage of etching, indicating that the etch-mechanism is different for each solution. Furthermore, when $H_3PO_4$ was added to the HCl aqueous solution, the morphology of the etched surface was greatly enhanced and the sidewall angle was also increased to about $65^{\circ}C$.
오수환,이철욱,김기수,고현성,박상기,박문호,이지면,Oh Su Hwan,Lee Chul-Wook,Kim Ki Soo,Ko Hyunsung,Park Sahnggi,Park Moon-Ho,Lee Ji-Myon 한국광학회 2004 한국광학회지 Vol.15 No.5
본 논문에서는 저 전류 및 고 효율로 동작하는 planar buried heterostructure(PBH) 구조로 sampled grating(SG) distributed bragg reflector(DBR) laser diode(LD)를 처음으로 설계하고 제작하였다. 특히 활성층과 도파로층의 높은 결합 효율을 얻기 위해 건식 식각과 습식 식각을 같이 사용하여 결함이 거의 없는 butt-coupling(BT) 계면을 형성하였다. 제작된 파장 가변레이저의 평균 발진 임계전류는 약 12 mA로 ridged waveguide(RWG)와 buried ridge stripe(BRS) 구조로 제작된 결과 보다 두 배 정도 낮게 나타났으며, 광 출력은 200 mA에서 약 20 mW 정도로 RWG 와 BRS 보다 각각 9 mW, 13 mW 더 우수하게 나타났다. 그리고 파장 가변 영역을 측정한 결과 44 nm로 설계결과와 일치하였으며, 최대 파장 가변 영역 안에서 출력 변화 폭이 5 dB 이내로서 RWG 구조의 9 dB보다 출력변화 폭이 4 dB 적게 나타났다. 전체 파장 가변 영역에서 SMSR이 35 dB 이상으로 나타났다. We have fabricated and designed wavelength-tunable sampled grating distributed Bragg reflector laser diodes(SGDBR-LD) by using, for the first time, planar buried heterostructures(PBH). The diodes have low threshold current values and high-performance of laser operation. Growth condition using metal organic chemical vapor deposition(MOCVD) was optimized for the formation of a good butt-coupling at the interface. A maximum output power of the fabricated device was 20 mW under 200 mA continuous wave(CW) operation at $25^{\circ}C$. Average threshold current and voltage were 12 mA and 0.8 V, approximately. This output power is higher than those of ridge waveguide(RWG) and buried ridge stripe(BRS) structures by amounts of 9 mW and 13 mW, respectively. We obtained a tuning range of 44.4nm which is well matched with the target value of our design. The side mode suppression ratio of more than 35 dB was obtained for the whole tuning range. Optical output power variation was less than 5 dB, which is 4 dB smaller than that of RWG structures.
p-GaN위에Roll-to-Rollsputter로성장된IZO의비저항및투과도에대한박막두께와열처리온도의영향
김준영 ( Jun Young Kim ),한승철 ( Seung Cheol Han ),김재관 ( Jae Kwan Kim ),김한기 ( Han Ki Kim ),이지면 ( Ji Myon Lee ) 대한금속재료학회 ( 구 대한금속학회 ) 2010 대한금속·재료학회지 Vol.48 No.6
We report on the characteristics of indium-oxide-doped ZnO (IZO) ohmic contact to p-GaN. The IZO ohmic contact layer was deposited on p-GaN by a Roll-to-Roll (RTR) sputter method. IZO contact film with a thickness of 360, 230 and 100 nm yielded an ohmic contact resistance of 4.70×10.4, 5.95×10.2, 4.85× 10.1 Ωcm2 on p-GaN when annealed at 600℃ for 1 min under a nitrogen ambient, respectively. While the transmittance of IZO film with a thickness of 360 nm slightly increased in the wavelength range of 380-800 nm after annealing, the transmittance rapidly increased up to 80% after annealing at 600℃ in the wavelength range of 380~430 nm because the crystallization of IZO film and created Ga vacancies near the p-GaN surface region were affected by the annealing. These results indicate that ohmic contact resistance and transmittance of the IZO films improved.
김재관 ( Jae Kwan Kim ),조영제 ( Young Je Jo ),한승철 ( Seung Cheol Han ),이혜용 ( Hae Yong Lee ),이지면 ( Ji Myon Lee ) 대한금속·재료학회 2009 대한금속·재료학회지 Vol.47 No.11
The surface morphology and the surface roughness of n-type SiC induced by wet-treatment using 45% KOH and buffered oxide etchant (BOE-1HF: 6H2O) were investigated by atomic force microscopy (AFM). While Si-face of SiC could be etched by alkali solutions such as KOH, acidic solutions such as BOE were hardly able to etch SiC. When the rough SiC samples were used, the surface roughness of etched sample was decreased after wet-treatment regardless of etchant, due to the planarization the of surface by widening of scratches formed by mechanical polishing. It was observed that the initial etching was affected by the energetically unstable sites, such as dangling bond and steps. However, when a relatively smooth sample was used, the surface roughness was rapidly increased after treatment at 180℃ for 1 hr and at room temperature for 4 hr by using KOH solution, resulting from the nano-sized structures such as pores and bumps. This indicates that porous SiC surface can be achieved by using purely chemical treatment.