Zn 농도변화에 따른 ZnO 박막의 구조, 광학 및 전기적 특성 연구

한호철,김익주,태원필,김진규,심문식,서수정,김용성 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.11

저온 박막 공정을 위해 비등점이 낮은 용매인 isopropanol을 사용하였고, 용질로 zinc acetate의 몰 농도를 0.3∼1.3 mol/l까지 변화시켜 sol을 합성하였다. Zn 농도 변화에 따른 ZnO 박막의 구조 및 광학, 전기적 특성을 분석하였다. XRD 측정에서 Zn의 농도가 0.7 mol/l 일 때 c-축으로 결정 배향성이 뚜렷하였다. SEM으로 박막의 표면 morphology를 관찰한 결과 0.7 mol/l 에서 균일한 표면층을 갖는 나노구조를 이루고 있었다. UV-vis. 측정을 통한 ZnO 박막의 광투과도는 Zn의 농도가 0.7 mol/l 이하에서 87%였으나, 1.0 mol/l 이상의 농도에서는 급격히 감소하였다. 이때 광 밴드갭 에너지는 3.07∼3.22 eV의 값을 나타내며, 벌크 ZnO의 특성과 유사하였다. 박막의 전기 비저항 값은 150 $\Omega$-cm로 Zn의 농도변화에 따라 큰 변화를 보이지 않았으며, I-V 특성분석에서 전형적인 ohmic contact 특성을 보였다. We used isopropanol which has low boiling point to prepare thin films at low temperature and changed mole concentration of zinc acetate from 0.3 to 1.3 mol/l. The structural, optical and electrical properties of ZnO thin films with Zn content were investigated. ZnO thin films highly oriented along the c-axis were obtained at Zn concentration of 0.7 mol/l. ZnO thin films with Zn concentration of 0.7 mol/l showed a homogeneous surface layer of nano structure. The transmittance of ZnO thin films by UV-vis. measurement was about 87% under the Zn concentration of 0.7 mol/l, but rapidly decreased over the 1.0 mol/l. The optical band gap energy was obtained from 3.07 to 3.22 eV which is very close to the band gap of bulk ZnO (3.2 eV). The electrical resistivity of ZnO thin films was about 150 $\Omega$-cm that shows little difference with Zn concentration. I-V curves of ZnO thin films exhibited typical ohmic contact properties.

Evaluation of the Photo-generated Carrier Density of GaAs Solar Cells by Using Electrical and Optical Biased Electroreflectance Spectroscopy

소모근,조현준,한임식,김종수,이상준,노삼규,임재영 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.4

In this work, to investigate the optical and the electrical properties of GaAs solar cells, we adopted optical/ electrical biased electroreflectance spectroscopy (ER) and current-voltage (J-V) measurements. The p-n junction’s electric fields were evaluated through an analysis of the Franz- Keldysh oscillations (FKOs) in the ER spectra. By comparing the electrical and the optical biased ER and optical biased J-V results, we calculated the carrier densities contributing to the photovoltage (pv) and the photocurrent (J ). We confirmed that the pv could affect the field screening for the p-n junction’s electric field. With increasing number of incident photons (ph), the ratio of pv to J was almost constant. From these results, for a concentrated photovoltaic device, we propose that the photovoltaic effect can affect the solar cell’s efficiency in the relatively high excitation intensity region.

Growth of Amino Substituted Anthracene Thin Films under Non Thermal Equilibrium Conditions

Sukhwinder Singh Brar,Aman Mahajan,R. K. Bedi 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.5

To enhance the performance and increase the lifetime of anthracene-based light emitting applications, thin films of amino substituted anthracene (1-Aminoanthracene and 2-Aminoanthracene) were prepared under non thermal equilibrium conditions using thermal evaporation technique onto the glass substrate kept at different temperatures. The prepared films were studied for their structural, optical and electrical properties. X-ray diffraction analysis indicated that 1-aminoanthracene deposited films were amorphous and 2-aminoanthracene films were polycrystalline in nature. The substrate temperature was found to significantly affect the morphology, electrical and optical properties. Films grown at elevated temperatures showed improved electrical conductivity. Besides these, the position of amino substitution showed significant effects on molecular packing and properties of films.

VO₂의 금속-절연체 전이 현상에 대한 광학적 특성 변화 측정

황인희 ( In-hui Hwang ),한상욱 ( Sang-wook Han ) 전북대학교 과학교육연구소 2018 과학과 과학교육 논문지 Vol.43 No.2

VO₂는 상온 근처에서 금속-절연체 전이 현상일 일어나는 것을 잘 알려진 물질이다. 금속과 절연체 전이 특성으로 인하여 전기적인 특성뿐만 아니라 광 특성에도 변화가 생긴다. 본 연구에서는 연구실의 레이저를 이용하여 간단하게 VO₂의 광 특성 변화를 측정할 수 있는 실험 방법을 보여준다. 또한 인 시투 기법으로 온도를 변화시키면서 광 특성과 전기적 특성의 변화를 동시에 측정하여 비교할 수 있도록 실험 장치를 설치하고 측정을 진행하였다. 이런 측정 기법은 다른 연구에도 널리 응용될 수 있을 것이다. VO₂ is a well-known metal-insulator transition (MIT) material with Tc of near room temperature. MIT causes a change of electrical properties and also optical properties. We demonstrated that optical property of VO₂ can be simply measured using a laser beam. The experiment was setup that optical properties were simultaneously measured with electrical properties as a function of temperature at in-situ condition. Therefore, the optical properties were directly compared to the electrical properties. This measurement technique can be widely applicable to other studies.

Electrical and Optical Properties in Transparent Conducting Oxides: Effect of Ultra Violet Irradiation

So, Byung-Soo,Hwang, Jin-Ha The Korean Society Of Semiconductor Display Techno 2007 반도체디스플레이기술학회지 Vol.6 No.1

A design of experiments was applied in order to investigate the effect of processing variables in UV irradiation on the electrical/optical properties in indium-zinc oxide thin films, The processing variables, equivalently input variables are listed as UV irradiation time, oxygen flow rate, and chamber pressure. The statistical significance of Ultra Violet (UV) treatment was confirmed using a paired-t test. The full factorial $2^3$ design was employed to determine significant main and interaction effects in UV irradiation process. The chamber pressure and the interaction between UV irradiation time and $O_2$ flow rate were found to be statistically significant at the significance level of 0.1. Furthermore, the optimized approach was proposed in achieving the improved conductivity after UV irradiation.

Enhanced Efficiency of Transmit and Receive Module with Ga Doped MgZnO Semiconductor Device by Growth Thickness

Bo-Hyun Shim,Hee-Jin Jo,Dong-Jin Kim,Jong-Mok Chae 대한전자공학회 2016 Journal of semiconductor technology and science Vol.16 No.1

The structural, electrical properties of Ga doped MgZnO transparent conductive oxide (TCO) films by ratio-frequency(RF) magnetron sputtering were investigated. Ga doped MgZnO TCO films were deposited on the sapphire substrates at 200℃ varying growth thickness 200 to 600 nm. The optical properties of Ga doped MgZnO TCO films were showed above 85% transmittance from 300 to 1000 nm region. In addition, the current density (JSC) of Cu(In,Ga)Se2 (CIGS) solar cells was improved by using the MgZnO:Ga films of 500 nm thickness because of outstanding electrical properties. The Cu(In,Ga)Se2 solar cells with MgZnO:Ga transparent conducing layer yielded an efficiency of 9.8% with current density (31.8 mA/cm<SUP>2</SUP>), open circuit voltage (540.2 V) and fill factor (62.2) under AM 1.5 illumination.

Enhanced Efficiency of Transmit and Receive Module with Ga Doped MgZnO Semiconductor Device by Growth Thickness

Shim, Bo-Hyun,Jo, Hee-Jin,Kim, Dong-Jin,Chae, Jong-Mok The Institute of Electronics and Information Engin 2016 Journal of semiconductor technology and science Vol.16 No.1

The structural, electrical properties of Ga doped MgZnO transparent conductive oxide (TCO) films by ratio-frequency(RF) magnetron sputtering were investigated. Ga doped MgZnO TCO films were deposited on the sapphire substrates at $200^{\circ}C$ varying growth thickness 200 to 600 nm. The optical properties of Ga doped MgZnO TCO films were showed above 85% transmittance from 300 to 1000 nm region. In addition, the current density ($J_{SC}$) of $Cu(In,Ga)Se_2$ (CIGS) solar cells was improved by using the MgZnO:Ga films of 500 nm thickness because of outstanding electrical properties. The $Cu(In,Ga)Se_2$ solar cells with MgZnO:Ga transparent conducing layer yielded an efficiency of 9.8% with current density ($31.8mA/cm^2$), open circuit voltage (540.2 V) and fill factor (62.2) under AM 1.5 illumination.

A Simulation Study on the Electrical Structure of Interdigitated Back-contact Silicon Solar Cells

강민구,송희은,김수민,김동환 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.10

In this paper, a simulation for interdigitated back-contact (IBC) silicon solar cells was performed by using Silvaco TCAD ATLAS to investigate the cell’s electrical properties. The impacts of various parameters, including the depth of the front surface field(FSF), the FSF peak doping concentration, the depths of the emitter and the back surface field(BSF), the peak doping concentrations of the emitter and BSF, the base doping, and the bulk lifetime on the output characteristics like the light current-voltage curves and the internal quantum efficiency of the IBC solar cell, were investigated. The light absorption was determined by adjusting the antireflection coating and the Al thickness. The FSF must be thin and have a low doping concentration for high-efficiency IBC cells. If the conversion efficiency is to be improved, a thick emitter and a high doping concentration are needed. Because of the low resistivity of the Si substrate, the series resistance was reduced, but recombination was increased. With a high-resistivity Si substrate, the opposite trends were observed. By counter-balancing the series resistance and the recombination, we determined by simulation that the optimized resistivity for the IBC cells was 1 ·cm. Because all metal electrodes in the IBC cells are located on the back side, a higher minority carrier lifetime showed a higher efficiency. After the various parameters had been optimized, texturing and surface recombination were added into the simulation. The simulated IBC cells showed a short-circuit current density of 42.89 mA/cm2, an open-circuit voltage of 714.8 mV, a fill factor of 84.04%, and a conversion efficiency of 25.77%.

Reversible Macroscopic Alignment of Ag Nanowires

Zhou, Hu,Heyer, Patrick,Kim, Ho-Jong,Song, Jung-Hoon,Piao, Longhai,Kim, Sang-Ho American Chemical Society 2011 Chemistry of materials Vol.23 No.16

<P>The macroscopic arrangement of one-dimensional nanowires (NWs)/nanorods is crucial for many technological applications, because of their structure-dependent physical properties. Using a simple flow-induced alignment method, reversible structural changes between aligned and random states were demonstrated in Ag NW suspensions. The alignment of the NWs was induced under high shear rates and was stable for at least 6000 s, because of depressed Brownian motion. An aligned Ag NW suspension could return to its original random state under low shear, because of the rotation of the Ag NWs. The practical implications of flow-induced alignment are shown through the dielectric, electric, and optical properties of the dispersions. Although the alignments were not perfect, these properties still exhibited marked direction dependence. It is remarkable that the macroscopic, reversible structural change between aligned and random states and the related changes of physical properties can be easily scalable to large areas for many potential applications.</P><P>Reversible alignment and disordering of Ag nanowires were demonstrated by shear. The critical shear rate is ca. 10 s<SUP>−1</SUP> for this reversible transition. Collective dielectric, electrical, and optical properties of Ag nanowires showed direction dependence after alignment.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2011/cmatex.2011.23.issue-16/cm200848h/production/images/medium/cm-2011-00848h_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm200848h'>ACS Electronic Supporting Info</A></P>

GAMMA RADIATION AND OZONE SENSING USING MIXED OXIDE THIN FILMS

O. KOROSTYNSKA,K. ARSHAK,G. HICKEY 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2008 NANO Vol.3 No.4

Gamma radiation and ozone sensing properties of mixed oxides in the form of thermally evaporated thin films are explored. External effects, such as radiation and ozone cause defects in the materials they interact with, cause changes in the material properties. An Edwards E306A thermal coating system was used for the mixed oxides thin films deposition. Cu electrodes were manufactured on the substrate via thermal evaporation, photoresist was spin-coated over it and was exposed to UV light via acetate containing the desired inter-digitated electrode patterns. After the exposure, the substrate was placed in a developer solution and then rinsed in water and placed in the etching solution to reveal the electrode pattern. The optical properties of the films were explored using CARY 1E UV-Visible Spectrophotometer. The influence of gamma radiation on the electrical properties of the films was traced via the measurements of conductance versus radiation dose, which were recorded in real-time using HP 4277A LCZ impedance analyzer at a frequency of 1 kHz. The fact that the explored thin films were sensitive to both gamma radiation and ozone exposure enables the development of cost-effective real-time monitoring system for personnel protection and environmental monitoring. This novel approach would allow the manufacture of the sensor system with multiple sensor heads during one technological process, whereas various shielding materials or pattern recognition could be employed to differentiate between the effects of ozone and gamma radiation on the mixed oxide thin film sensors.