• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.88-88
• /
• 2011

ZnO는 직접 천이형 반도체로써, 상온에서 3.4eV에 해당하는 띠틈을 가지고 있다. 뿐만 아니라 60meV의 큰 엑시톤 결합에너지를 가지고 있어 단파장 광전 소자 영역의 LED(Light Emitting Diode)나 LD(Laser Diode)에 널리 사용되고 있다. 하지만 일반적으로 격자틈새 Zn(Zni2+)이온이나 O 빈자리(V02+)이온과 같은 자연적인 도너 이온이 존재하여 n-형 전도성을 나타낸다. 그러므로 ZnO계 LED와 LD의 개발에 있어서 가장 중요한 연구 과제는 재현성 있고 안정된 고농도의 p-형 ZnO박막을 성장시키는 것이다. 하지만, 자기보상효과나 얕은 억셉터 준위, 억셉터의 낮은 용해도로 인하여 어려움을 가지고 있다. 본 연구에서는 고품질의 p-형 ZnO박막을 제작하기 위해 AlN를 도핑시킨 ZnO박막을 RF 마그네트론 스퍼터링 법을 이용하여 Ar과 O2분위기에서 성장시켰다. ZnO와 AlN타겟을 동시에 사용하였으며, ZnO타겟에 걸어준 RF 파워는 80W, AlN타겟에 걸어준 RF 파워는 5~20W로 변화시켰다. 박막의 전기적, 광학적 특성은 XPS (X-ray Photoelectron Spectroscopy), REELS (Reflection Electron Energy Loss Spectroscopy), XRD (X-ray Diffraction), SIMS (Secondary Ion Mass Spectrometry), AES (Auger Electron Spectroscopy), Hall measurement를 이용하여 연구하였다. XPS측정결과, AlN를 도핑시킨 ZnO박막의 Zn2p3/2와 O1s피크는 undoped ZnO박막의 피크보다 낮은 결합에너지에서 측정되었다. 모든 박막이 결정화 되었으며, (002)방향으로 우선적으로 성장된 것을 확인할 수 있었다. 홀 측정 결과, 기판을 $200^{\circ}C$로 가열하면서 성장시킨 박막이 p-형을 나타내었으며, 비저항(Resistivity)이 $5.51{\times}10^{-3}{\Omega}{\cdot}m$, 캐리어 농도(Carrier Concentration)가 $1.96{\times}1018cm^{-3}$, 이동도(Mobility)가 $481cm^2$/Vs이었다. 또한 QUEELS -Simulation에 의한 광학적 특성분석 결과, 가시광선영역에서 투과율이 90%이상으로 투명전자소자로의 응용이 가능하다는 것을 보여주었다.

• Korean Journal of Materials Research
• /
• v.2 no.1
• /
• pp.35-42
• /
• 1992

Thermal behavior of residue and damaged layer formed by reactive ion etching (RIE) in $CHF_3/C_2F_6$ were investigated using X-ray photoelectron spectroscopy(XPS) and secondary ion mass spec-trometry(SIMS) techniques. Decomposition of polymer residue film begins at $200^{\circ}C$ and above $400^{\circ}C$ carbon compound as graphite mainly forms by in-situ resistive heating. It reveals that thermal decomposition of residue can be completed by rapid thermal anneal treatment above $800^{\circ}C$ under nitrogen atmosphere and out-diffusion of carbon and fluorine of damaged layer is observed.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.274-274
• /
• 2012

In-depth analysis by secondary ion mass spectrometry (SIMS) is very important for the development of electronic devices using multilayered structures, because the quantity and depth distribution of some elements are critical for the electronic properties. Correct determination of the interface locations is critical for the calibration of the depth scale in SIMS depth profiling analysis of multilayer films. However, the interface locations are distorted from real ones by the several effects due to sputtering with energetic ions. In this study, the determination of interface locations in SIMS depth profiling of multilayer films was investigated by Si/Ge and Ti/Si multilayer systems. The original SIMS depth profiles were converted into compositional depth profiles by the relative sensitivity factors (RSF) derived from the atomic compositions of Si-Ge and Si-Ti alloy reference films determined by Rutherford backscattering spectroscopy. The thicknesses of the Si/Ge and Ti/Si multilayer films measured by SIMS depth profiling with various impact energy ion beam were compared with those measured by TEM. There are two methods to determine the interface locations. The one is the feasibility of 50 atomic % definition in SIMS composition depth profiling. And another one is using a distribution of SiGe and SiTi dimer ions. This study showed that the layer thicknesses measured with low energy oxygen and Cs ion beam and, by extension, with method of 50 atomic % definition were well correlated with the real thicknesses determined by TEM.

• Korean Journal of Materials Research
• /
• v.1 no.4
• /
• pp.214-220
• /
• 1991

The effects of $SiO_2$ reactive ion etching (RIE) in $CHF_{3/}C_2F_6$ on the surface properties of the underlying Si substrate were studied by X-ray photoelectron spectroscopy(XPS) and secondary ion mass spectrometry(SIMS) techniques. Angle-resolved XPS analysis was carried out as non-destructive depth profile one for investigating the chemical bonding states of silicion, carbon, oxygen and fluorine. The residue layer consists of C-F polymer. O-F bond was found on the top of the polymer layer and Si-O, Si-C and Si-F bonds were detected between Si substrate and polymer film. A 60nm thick damaged layer of silicon surface mainly contains carbon and fluorine.

• Korean Journal of Materials Research
• /
• v.24 no.9
• /
• pp.488-494
• /
• 2014

The effect of tungsten (W) addition on the hardenability of low-carbon boron steels was investigated using dilatometry, microstructural observations and secondary ion mass spectroscopy. The hardenability was discussed with respect to transformation behaviour aspects depending on the segregation and precipitation of boron at austenite grain boundaries. A critical cooling rate producing a hardness corresponding to 90 % martensite structure was measured from a hardness distribution plot, and was used as a criterion to estimate hardenability at faster cooling rates. In the low-carbon boron steel, the addition of 0.50 wt.% W was comparable to that of 0.20 wt.% molybdenum in terms of critical cooling rate, indicating hardenability at faster cooling rates. However, the addition of 0.50 wt.% W was not more effective than the addition of .0.20 wt.% molybdenum at slower cooling rates. The addition of 0.20 wt.% molybdenum completely suppressed the formation of eutectoid ferrite even at the slow cooling rate of $0.2^{\circ}C/s$, while the addition of 0.50 wt.% W did not, even at the cooling rate of $1.0^{\circ}C/s$. Therefore, it was found that the effect of alloying elements on the hardenability of low-carbon boron steels can be differently evaluated according to cooling rate.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.59.1-59.1
• /
• 2015

In the Linford group at Brigham Young University we have recently developed three new sets of materials for three different areas of separations science: thin layer chromatography (TLC), high performance liquid chromatography (HPLC), and solid phase microextraction (SPME). First, via microfabrication we have grown patterned carbon nanotube (CNT) forests on planar substrates that we have infiltrated with inorganic materials such as silicon nitride. The coatings on the CNTs are conformal and typically deposited in a process like low pressure chemical vapor deposition. The resulting materials have high surface areas, are porous, and function as effective separation devices, where separations on our new TLC plates are typically significantly faster than on conventional devices. Second, we used the layer-by-layer (electrostatically driven) deposition of poly (allylamine) and nanodiamond onto carbonized poly (divinylbenzene) microspheres to create superficially porous particles for HPLC. Many interesting classes of molecules have been separated with these particles, including various cannabinoids, pesticides, tricyclic antidepressants, etc. Third, we have developed new materials for SPME by sputtering silicon onto cylindrical fiber substrates in a way that creates shadowing of the incoming flux so that materials with high porosity are obtained. These materials are currently outperforming their commercial counterparts. Throughout this work, the new materials we have made have been characterized by X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, scanning electron microscopy, transmission electron microscopy, etc.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05b
• /
• pp.16-19
• /
• 2002

(Ba,Sr)TiO3(BST) thin film is an attractive material for the application in high-density dynamic random access memories (DRAMs) because of the high relative dielectric constant and small variation in dielectric properties with frequency. In this study, (Ba0.6,Sr0.4)TiO3 thin films on Pt/Ti/SiO2/Si substrates were deposited by a sol-gel method and the CF4/Ar inductively coupled plasma (ICP) etching behavior of BST thin films had been investigatedby varying the process parameters such as chamber pressure, ICP power, and substrate bias voltage. To analysis the composition of surface residue following etching BST films etched with different Ar/CF4 gas mixing ratio were investigated using x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometer (SIMS).

• Electrical & Electronic Materials
• /
• v.16 no.9
• /
• pp.65.1-65
• /
• 2003

The interface of zirconium oxide thin films on silicon is analyzed in detail for their potential applications in the microelectronics. The formation of an interfacial layer of ZrSi$\sub$x/O$\sub$y. with graded Zr concentration is observed by the x-ray photoelectron spectroscopy and secondary ion mass spectrometry analysis. The as-deposited ZrO$_2$/ZrSi$\sub$x/O$\sub$y//Si sample is thermally stable up to 880$^{\circ}C$, but is less stable compared to the ZrO$_2$/SiO$_2$/Si samples. Post-deposition annealing in oxygen or ammonia improved the thermal stability of as-deposited ZrO$_2$/ZrSi$\sub$x/O$\sub$y/Si to 925$^{\circ}C$, likely due to the oxidation/nitridation of the interface. The as-deposited film had an equivalent oxide thickness of∼13 nm with a dielectric constant of ∼21 and a leakage current of 3.2${\times}$10e-3 A/$\textrm{cm}^2$ at 1.5V. Upon oxygen or ammonia annealing, the formation of SiO$\sub$x/ and SiH$\sub$x/N$\sub$y/O$\sub$z/ at the interface reduced the overall dielectric constants.

• Korean Journal of Materials Research
• /
• v.28 no.10
• /
• pp.564-569
• /
• 2018

$Cu_2ZnSn(S,Se)_4$ (CZTSSe) films were prepared on Mo coated soda lime glass substrates by sulfo-selenization of sputtered stacked Zn-Sn-Cu(CZT) precursor films. The precursor was dried in a capped state with aqueous NaOH solution. The CZT precursor films were sulfo-selenized in the S + Se vapor atmosphere. Sodium was doped during the sulfo-selenization treatment. The effect of sodium doping on the structural and electrical properties of the CZTSSe thin films were studied using FE-SEM(field-emission scanning electron microscopy), XRD(X-ray diffraction), XRF(X-ray fluorescence spectroscopy), dark current, SIMS(secondary ion mass spectrometry), conversion efficiency. The XRD, XRF, FE-SEM, Dark current, SIMS and cell efficiency results indicated that the properties of sulfo-selenized CZTSSe thin films were strongly related to the sodium doping. Further detailed analysis and discussion for effect of sodium doping on the properties CZTSSe thin films will be discussed.

• Journal of the Korean Vacuum Society
• /
• v.6 no.4
• /
• pp.321-325
• /
• 1997

Recently, photosensitive color filters have received much attention for their use in the liquid crystal display (LCD) industry. It is well known that chemical and physical properties of polymer surfaces can be modified by special surface treatments. In this work, we have studied the polymer surfaces of LCD blue color filters which were exposed to the UV light during photolithography. A better understanding of the irradiated polymer surfaces is required for the subsequent processes such as plasma etching, ITO electrode deposition, etc. The surface analysis has been undertaken using secondary ion mass spectrometry (SIMS), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). A significant enrichment of the pigment component and roughening of surface with bubble-like feature have been observed at the modified polymer surface.