• Laser Solutions
• /
• v.17 no.4
• /
• pp.7-13
• /
• 2014

In this work, the application of laser induced breakdown spectroscopy (LIBS) for the composition analysis of thin $Cu(In,Ga)Se_2$ (CIGS) solar cell films ($1-2{\mu}m$ thickness) is reported. For the ablation of CIGS films, femtosecond (fs) laser (wavelength = 343nm, pulse width = 500fs) and nanosecond (ns) laser (wavelength = 266nm, pulse width = 5ns) were used under atmospheric environment. The emission spectra were detected with an intensified charge coupled device (ICCD) spectrometer and multichannel CCD spectrometer for fs-LIBS and ns-LIBS, respectively. The calibration curves for fs-LIBS and ns-LIBS intensity ratios of Ga/Cu, In/Cu, and Ga/In were generated with respect to the concentration ratios measured by inductively coupled plasma optical emission spectrometry (ICP-OES).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.3
• /
• pp.1259-1264
• /
• 2014

Hydrogen is in the world limelight for future energy source, and it has been already used in various industry fields including aerospace. The extremely fine molecule of the hydrogen can be easily leaked from tiny size of the crack on the surface of transporting pipes or storage tanks, and it could bring on awfully terrible disaster. In this study, Laser-Induced Breakdown Spectroscopy (LIBS) was employed to develope a reliable detection scheme for a small quantity of hydrogen leakage. Effect of three different metal substrates (i.e. Al, Cu, SUS) on plasma generation and the intensity of the hydrogen atomic signal was investigated, and the surface damage of the substrates due to repetitive laser shots was observed using Scanning electron microscope. It was also evaluated how the surface damage could distort the atomic signal. The intensity of the atomic signal was found to be the strongest, and the signal distortion due to the surface damage was approximately $100W/m^2$ lower when Al was used for the substrate.

• Journal of the Optical Society of Korea
• /
• v.17 no.6
• /
• pp.548-558
• /
• 2013

In this work, laser induced breakdown spectroscopy (LIBS) is used to investigate soil samples collected from different desert areas of Riyadh city in Saudi Arabia. Both qualitative analysis and plasma parameters are studied via the observed LIBS spectra. These experiments have been done using a Spectrolaser-7000 system with 50 mJ fundamental wavelength of Nd:YAG laser and detection delay time of 1 microsecond. Many spectral lines are highly resolved for many elements like Al, Fe, Mg, Si, Mn, Na, Ca and K. The electron temperatures Te and electron densities Ne, for the constituent of generated LIBS plasma, are determined for all the collected samples. It is found that both Te and Ne vary from one desert area to other. This variation is due to the change of the elemental concentration in different desert areas that affects the sample's matrices. Time dependent measurements have also been performed on the soil samples. While the signal-to-base ratio (SBR) reached its optimal value at 1 microsecond, the plasma parameters Ne and Te reach values of $4{\times}10^{17}cm^{-3}$ and 9235 K, respectively, at 2.5 microsecond. The later indicate that the plasma cooling processes are slow in comparison to the previously observed results for metallic samples. The observed results show also that in the future it is possible to enhance the exploitation of LIBS in the remote on-line environmental monitoring application, by following up only the values of Ne and Te for one element of the soil desert sample using an optical fiber probe.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.236.1-236.1
• /
• 2014

Compounds of Ga, such as gallium oxide (Ga2O3) and gallium nitride (GaN), are of interest due to its unique properties in semiconductor application. In particular, GaN has the potentially application for optoelectronic device such as light-emitting diodes (LEDs) and laser diodes (LDs) [1]. Nanoparticle is an interesting material due to its unique properties compared to the bulk equivalents. In this report, we develop a synthesizing method for gallium nitride nanoparticle using non-thermal plasma. For gallium source, the gallium is heated by thermal conduction of tungsten boat which is heated by eddy current induced from RF current in antenna. Nitrogen source for nanoparticle synthesis are from inductively coupled plasma with N2 gas. The synthesized nano particles are analyzed using field-emission scanning microscope (FESEM), transmission electron microscope (TEM) and x-ray photoelectron spectroscopy (XPS). The synthesized particles are investigated and discussed in wide range of experiment conditions such as flow rate, pressure and RF power.

• Analytical Science and Technology
• /
• v.26 no.4
• /
• pp.235-244
• /
• 2013

Detection of halogens using laser-induced breakdown spectroscopy (LIBS) in open air is very difficult since their strong atomic emission lines are located in VUV region. In NIR region, there are other emission lines of halogens through electronic transitions between excited states. However, these lines undergo Stark broadening severely. We report the observation of the emission lines of halogens in laser-induced plasma (LIP) spectra in NIR region using a helium gas flow. Particularly, the emission lines of iodine at 804.374 and 905.833 nm from LIPs have been observed for the first time. In the helium ambient gas, Stark broadening of the emission lines and background continuum emission could be suppressed significantly. Variations of the line intensity, plasma temperature, and electron density with the helium flow rate was investigated. Detection of chlorine and bromine in flame retardant of rubbers was demonstrated using this method. Finally, we suggest a pulsed helium gas jet as a practical and ecomonical helium gas source for the LIBS analysis of halogens in open air.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2000.01a
• /
• pp.175-176
• /
• 2000

Electric fields and the wall voltages in a surface-type AC PDP cell were measured using a Laser Induced Fluorescence Spectroscopy. For the condition of He 100Torr, 200V sustain voltage and 50kHz sustain frequency, the wall voltage dropped from about 50V to about -75V within $1{\mu}sec$ after the main discharge. And the wall voltage decreased with the rate of $10.8V/{\mu}sec$ due to the accumulation of the space charges after $1{\mu}sec$. But when the operating pressure was 40Torr, it increased with the rate of $4.5V/{\mu}sec$ because the diffusion effect of the wall charge on MgO surface was more dominant than the accumulation effect of the space charges. During the pulse-off period, the wall voltage decreased slightly due to the diffusion of the wall charge. When the sustain voltage was 250V, the self-erasing discharge occurred, and the absolute value of the wall voltage decreased rapidly just after the pulses were off, which was caused by the accumulation of the charges generated by the self-erasing discharge.

• Economic and Environmental Geology
• /
• v.40 no.5
• /
• pp.563-574
• /
• 2007

Laser induced breakdown spectroscopy (LIBS) is a recently developed analytical technique that is based upon the measurement of emission lines generated by atomic species close to the surface of the sample, thus allowing their chemical detection, identification and quantification. With powerful advantages of LIBS compared to the conventional analytical methodology, this technique can be applied in the detection of heavy metals in the field. LIBS allows the rapid analysis by avoiding laborious chemical steps. LES have already been applied for the determination of element concentration in a wide range of materials in the solid, liquid and gaseous phase with simplicity of the instrument and diversity of the analytical application. These feasibility of rapid multi elemental analysis are appealing proprieties for the in-situ analytical technique in geochemical investigation, exploration and environmental analysis. There remain still some limitations to be solved for LIBS to be applied in soil environment as an in-situ analytical technology. We would like to provide the basic principle related to the plasma formation and laser-induced breakdown of sample materials. In addition, the matrix effect, laser properties and the various factors affecting on the analytical signal of LIBS was dealt with to enhance understanding of LIBS through literature review. Ultimately, it was investigated the feasibility of LIBS application in soil environment monitoring by considering the basic idea to enhance the data quality of LIBS including the calibration method for the various effects on the analytical signal of LIBS.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.313-313
• /
• 2013

For high-performance TFT (Thin film transistor), poly-crystalline semiconductor thin film with low resistivity and high hall carrier mobility is necessary. But, conventional SPC (Solid phase crystallization) process has disadvantages in fabrication such as long annealing time in high temperature or using very expensive Excimer laser. On the contrary, MIC (Metal-induced crystallization) process enables semiconductor thin film crystallization at lower temperature in short annealing time. But, it has been known that the poly-crystalline semiconductor thin film fabricated by MIC methods, has low hall mobility due to the residual metals after crystallization process. In this study, Ni metal was shallow implanted using PIII&D (Plasma Immersion Ion Implantation & Deposition) technique instead of depositing Ni layer to reduce the Ni contamination after annealing. In addition, the effect of external magnetic field during annealing was studied to enhance the amorphous silicon thin film crystallization process. Various thin film analytical techniques such as XRD (X-Ray Diffraction), Raman spectroscopy, and XPS (X-ray Photoelectron Spectroscopy), Hall mobility measurement system were used to investigate the structure and composition of silicon thin film samples.

• Korean Journal of Soil Science and Fertilizer
• /
• v.42 no.5
• /
• pp.399-407
• /
• 2009

Laser induced breakdown spectroscopy(LIBS) is an simple analysis method for directly quantifying many kinds of soil micro-elements on site using a small size of laser without pre-treatment at any property of materials(solid, liquid and gas). The purpose of this study were to find an optimum condition of the LIBS measurement including wavelengths for quantifying soil elements, to relate spectral properties to the concentration of soil elements using LIBS as a simultaneous un-breakdown quantitative analysis technology, which can be applied for the safety assessment of agricultural products and precision agriculture, and to compare the results with a standardized chemical analysis method. Soil samples classified as fine-silty, mixed, thermic Typic Hapludalf(Memphis series) from grassland and uplands in Tennessee, USA were collected, crushed, and prepared for further analysis or LIBS measurement. The samples were measured using LIBS ranged from 200 to 600 nm(0.03 nm interval) with a Nd:YAG laser at 532 nm, with a beam energy of 25 mJ per pulse, a pulse width of 5 ns, and a repetition rate of 10 Hz. The optimum wavelength(${\lambda}nm$) of LIBS for estimating soil and plant elements were 308.2 nm for Al, 428.3 nm for Ca, 247.8 nm for T-C, 438.3 nm for Fe, 766.5 nm for K, 85.2 nm for Mg, 330.2 nm for Na, 213.6 nm for P, 180.7 nm for S, 288.2 nm for Si, and 351.9 nm for Ti, respectively. Coefficients of determination($r^2$) of calibration curve using standard reference soil samples for each element from LIBS measurement were ranged from 0.863 to 0.977. In comparison with ICP-AES(Inductively coupled plasma atomic emission spectroscopy) measurement, measurement error in terms of relative standard error were calculated. Silicon dioxide(SiO2) concentration estimated from two methods showed good agreement with -3.5% of relative standard error. The relative standard errors for the other elements were high. It implies that the prediction accuracy is low which might be caused by matrix effect such as particle size and constituent of soils. It is necessary to enhance the measurement and prediction accuracy of LIBS by improving pretreatment process, standard reference soil samples, and measurement method for a reliable quantification method.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.217-217
• /
• 2011

플라즈마를 이용하는 식각 및 증착등의 반도체공정에 있어서 최근에는 기판의 크기가 점차 증가하는 추세에 있다. 이러한 대면적 플라즈마 발생장치 내에서 플라즈마 밀도와 라디칼 농도의 공간적인 특성을 이해하는 것에 대한 중요성이 더해지고 있다. 이를 위해 Langmuir probe와 같은 전기적 접근법에 의한 진단방법이나 광학적 접근법에 의한 진단방법에 대한 연구가 이루어 졌다. 전기적 접근법에 의한 플라즈마의 진단방법은 원리가 간단하고 정확도가 높다는 장점이 있지만 진단 장치에 의한 플라즈마의 간섭이 크고 식각가스의 경우 진단이 어렵다는 단점이 있다. 그에 비해 광학적 진단방법은 플라즈마에 간섭이 많지 않은 방법으로 알려져 있고 레이저 형광법(LIF), 원적외선 레이저 흡수 분광법(IR laser Absorption Spectroscopy), 광량측정법(Actinometry)등이 있다. 이 중 레이저 형광법, 원적외선 레이저 흡수 분광법의 경우, 진단장치가 매우 복잡하고 가격이 비싸다는 단점을 가지고 있다. 반면 광량측정법의 경우 다른 광학적 접근법에 의한 진단방법에 비해 원리와 실험장치가 간단하고 공간적인 라디칼 분포의 진단이 쉽다는 점에서 장점을 가지고 있다. Actinometry는 Ar과 같은 불활성 기체를 작은 비율을 넣어서 여기 된 불활성 기체의 파장세기와 여기 된 측정 라디칼의 파장세기의 비교를 통해 상대밀도를 측정하는 방법이다. 이 측정 방법에 Abel's inversion equation을 적용함으로 해서 대면적 M-ICP(Magnetized - Induced Coupled Plasma)에서 식각가스인 $CF_4$플라즈마에서 F 라디칼 농도의 공간적인 분포를 측정하고 분석하였다. 또한 플라즈마의 압력, 소스 전력 값과 기판 전력 값등의 조건의 변화에 따라 F 라디칼 농도의 분포가 어떻게 달라지는지에 대해 측정 분석하여 다루었다.