• Korean Journal of Materials Research
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• v.30 no.10
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• pp.566-572
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• 2020

In the recent years, thin film solar cells (TFSCs) have emerged as a viable replacement for crystalline silicon solar cells and offer a variety of choices, particularly in terms of synthesis processes and substrates (rigid or flexible, metal or insulator). Among the thin-film absorber materials, SnS has great potential for the manufacturing of low-cost TFSCs due to its suitable optical and electrical properties, non-toxic nature, and earth abundancy. However, the efficiency of SnS-based solar cells is found to be in the range of 1 ~ 4 % and remains far below those of CdTe-, CIGS-, and CZTSSe-based TFSCs. Aside from the improvement in the physical properties of absorber layer, enormous efforts have been focused on the development of suitable buffer layer for SnS-based solar cells. Herein, we investigate the device performance of SnS-based TFSCs by introducing double buffer layers, in which CdS is applied as first buffer layer and ZnMgO films is employed as second buffer layer. The effect of the composition ratio (Mg/(Mg+Zn)) of RF sputtered ZnMgO films on the device performance is studied. The structural and optical properties of ZnMgO films with various Mg/(Mg+Zn) ratios are also analyzed systemically. The fabricated SnS-based TFSCs with device structure of SLG/Mo/SnS/CdS/ZnMgO/AZO/Al exhibit a highest cell efficiency of 1.84 % along with open-circuit voltage of 0.302 V, short-circuit current density of 13.55 mA cm^-2, and fill factor of 0.45 with an optimum Mg/(Mg + Zn) ratio of 0.02.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.171-173
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• 2001

ZnO:Al transparent conductive thin films were prepared by facing targets sputtering system with a DC power supply using ZnO target containing 2wt% of $Al_2O_3$ and Zn metal target. Sputtering was carried out at substrate temperature of R.T. and $200^{\circ}C$ with a DC current of 0.6A, $O_2$ flow rate of $0.1{\sim}0.5$ and thickness $300{\sim}900nm$. ZnO:Al films showed a resistivity as low as $10^{-4}{\Omega}-cm$ and a transmittance above 85 % at wavelength 300 and 800nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.55-56
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• 2005

The properties of phosphorus doped ZnO thin films deposited on (001) sapphire substrates by pulsed laser deposition (PLD) were investigated depending on various deposition conditions. The phosphorus (P) doped ZnO target was composed of ZnO + x wt% Al (x=1, 3, 5). The structural, electrical and optical properties of the ZnO thin films were measured by X-ray diffraction (XRD), Hall measurements and photoluminescence (PL). As the deposition temperature optimized, the electrical properties of the phosphorus doped ZnO (ZnO:P) layer showed a electron concentration of $7.76\times10^{16}/cm^3$, a mobility of 10.225 $cm^2/Vs$, a resistivity of 7.932 $\Omega$cm. It was observed the electrical property of the film was changed by dopant activation effect as target variations and deposition conditions.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.527-530
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• 2009

We report on the fabrication of ZnO-based dual gate (DG) thin-film transistors (TFTs) with 20 nm-thick $Al_2O_3$ for both top and bottom dielectrics, which were deposited by atomic layer deposition on glass substrates at $200^{\circ}C$. Whether top or bottom gate is biased for sweep, our TFT almost symmetrically operates under a low voltage of 5 V showing a field mobility of ~0.4 $cm^2/V{\cdot}s$ along with the on/off ratio of $5{\times}10^4$. The threshold voltage of our DG TFT was systematically controlled from 0.5 to 2.0 V by varying counter gate input from +5 to -2 V.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.315-322
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• 2002

A thin film oxide semiconductor micro gas sensor array which shows only 60㎽ of power consumption at an operating temperature of 30$0^{\circ}C$ has been fabricated using microfabrication and rnicrornachining techniques. Excellent thermal insulation of the membrane is achieved by the use of a double la! or structure of 0.1${\mu}{\textrm}{m}$ thick Si$_3$N$_4$ and 1${\mu}{\textrm}{m}$ thick phosphosilicate glass(PSG) prepared by low pressure chemical vapor deposition(LPCVD) and atmospheric－pressure chemical-vapor deposition(APCVD), respectively. The sensor way consists of such thin film oxide semiconductor sensing materials as 1wt.％ Pd-doped SnO$_2$, 6wt.% AI$_2$O$_3$-doped ZnO, WO$_3$ and ZnO. The thin film oxide semiconductor micro gas sensor array exhibited resistance changes usable for subsequent data processing upon exposure to various gases and the sensitivity strongly depended on the sensing layer materials. Heater Part of the sensor structure has been modified in order to improve the process yield of the sensor, and as a result of modified heater structure improved process yield has been achieved.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.159-159
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• 2009

RF 스퍼터링법을 이용하여 유리기판위에 ZnO:Al 박막을 증착하고 다양한 조건 하에서 후 열처리를 실시하여 이에 따른 박막의 구조적, 전기적 및 광학적 특성과 HCl 습식 식각 후의 표면형상 변화를 조사하였다. ZnO:Al 투명전도막은 우수한 전기적, 광학적 특성, 수소 플라즈마 안정성 및 저 비용 등으로 실리콘 박막 태양전지 전면 전극용으로 많은 관심을 받고 있다. 기존의 비정질 실리콘 박막 태양전지용으로 많이 사용되고 있는 상용 Asahi-U형 ($SnO_2:F$) 투명전도막의 경우는 수소 플라즈마에 대한 안정성이 낮고 입사광의 장파장 대역에서의 낮은 산란특성으로 인하여 실리콘 박막 태양전지의 고효율화를 위한 적용에 한계를 나타내고 있다. 이를 개선하기 위하여 스퍼터링법으로 우수한 전기적 특성을 갖는 ZnO:Al 박막을 제조한 후 습식 식각을 통한 표면형상 변화를 통하여 입사광의 산란특성을 향상시키는 방법이 개발되어 많은 연구가 이루어지고 있다. 본 연구에서는 2.5 wt%의 $Al_2O_3$가 함유된 ZnO 타겟을 이용하여 ZnO:Al 박막을 RF 스퍼터링으로 증착한 후 $N_2$ 분위기와 진공 분위기 하에서 다양한 시간과 온도에 따라 후열처리를 하여 열처리 전 박막과의 물질 특성을 상호 비교하고 1%로 희석된 HCl로 습식 식각하여 열처리 전 박막의 구조적 특성이 습식 식각 후의 박막 표면형상 변화에 미치는 영향을 조사하였다. 이로부터 후열처리를 통한 ZnO:Al 투명전도막의 특성을 최적화하고 Asahi-U형 투명전도막과의 특성 비교를 통하여 실리콘 박막 태양전지용 전면전극으로의 적용 가능성을 조사하였다.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1523-1525
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• 2003

Due to the rapid development of wireless networking system, researches on the communication devices are mainly focus on microwave frequency devices such as filters, resonators, and phase shifters. Among them, Film bulk acoustic resonator (FBAR) has been paid extensive attentions for their high performance. In this research, ZnO thin films were deposited by RF-magnetron sputtering on Al/$SiO_2$/Si wafer and then crystalline properties and surface morphology were examined. To measure crystalline structure and surface morphology X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) were employed. It was showed that crystalline properties of ZnO thin films were strongly dependant on the deposition conditions. As increasing the deposition temperature and the deposition pressures, the peak intensities of ZnO(002) plane were increased until $300^{\circ}C$, then decreased rapidly. At the sputtering conditions of RF power of 213 W and working pressure of 15 m Torr, ZnO film had excellent c-axis orientation, surface morphology, and adhesion to the substrate. In conclusion we optimized smooth surface with very small grains as well as highly c-axis oriented ZnO film for FBAR applications.

• Journal of the Korean Ceramic Society
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• v.48 no.4
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• pp.328-333
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• 2011

The influence of Al-doped ZnO (AZO) thin films degraded under high temperature and damp heat on the performance deterioration of Cu(In,Ga)$Se_2$ (CIGS) solar cells was investigated. CIGS solar cells with AZO/CdS/CIGS/Mo structure were prepared on glass substrate and exposed to high temperature ($85^{\circ}C$) and damp heat ($85^{\circ}C$/85% RH) for 1000 h. As-prepared CIGS solar cells had 64.91% in fill factor (FF) and 12.04% in conversion efficiency. After exposed to high temperature, CIGS solar cell had 59.14% in FF and 9.78% in efficiency, while after exposed to damp heat, it had 54.00% in FF and 8.78% in efficiency. AZO thin films in the deteriorated CIGS solar cells showed increases in resistivity up to 3.1 times and 4.4 times compared to their initial resistivity after 1000 h of high temperature and damp heat exposure, respectively. These results can be explained by the decreases in carrier concentration and mobility due to diffusion or adsorption of oxygen and moisture in AZO thin films. It can be inferred that decreases in FF and conversion efficiency were caused by an increase in series resistance, which resulted from an increase in resistivity of AZO thin films degraded under high temperature and damp heat.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.688-692
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• 2004

In this paper, zinc oxide (ZnO) films with c-axis (002) orientation have been successfully deposited on the Al/Si substrate by rf magnetron sputtering method. The deposited films were characterized by substate temperature. Physical and structural properties of the deposited films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurement. Electrical Properties of the deposited films were investigated by 4-poing probe and LCR meter measurement. The optimal condition in this experimental result was found at foot of the substrate temperature and shown good film quality for FBAR application.

• Journal of Sensor Science and Technology
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• v.5 no.1
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• pp.30-36
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• 1996

ZnO thin-film sensors were fabricated by RF magnetron sputtering method. The composition of the device material was 4 wt. % $Al_{2}O_{3}$, 1 wt. % $TiO_{2}$ and 0.2 wt. % $V_{2}O_{5}$ on the basis of ZnO material for developing the high sensitive TMA gas sensor which have an appropriate resistivity and the stability for practical use. They were also grown on the $SiO_{2}/Si$ substrates heated at $250^{\circ}C$ under a pure oxygen pressure of about 10 mTorr with a power of about 80 watts for 10 minutes. So as to enhance the stability of the resistivity, the thin films were annealed from $400^{\circ}C$ to $800^{\circ}C$. The sensors made with the thin film which were annealed at $700^{\circ}C$ for 60 minutes in pure oxygen gas exhibited a good sensing properties for TMA gas. The thin film grown at this condition showed the maximum sensitivity of 550 in TMA gas concentration of 160 ppm, and exhibited a good stability and excellent linearity.