• Current Photovoltaic Research
• /
• 제3권1호
• /
• pp.21-26
• /
• 2015

High efficiency $Cu(In,Ga)Se_2$ solar cells are generally prepared above $500^{\circ}C$. Lowering the process temperature can allow wider selection of substrate material and process window. In this paper, the three-stage co-evaporation process widely used to grow CIGS thin film at high temperature was modified to reduce the maximum substrate temperature. Below $400^{\circ}C$ the CIGS films show poor crystal growth and lower solar cell performance, in spite of external Na doping by NaF. As a new approach, Cu source instead of Cu with Se in the second stage was applied on the $(In,Ga)_2Se_3$ precursor at $400^{\circ}C$ and achieved a better crystal growth. The distribution of Ga in the films produce by new method were investigated and solar cells were fabricated using these films.

• Current Photovoltaic Research
• /
• 제5권4호
• /
• pp.135-139
• /
• 2017

We fabricated two different transparent conducting oxide thin films of ZnO doped with Ga ($Ga_2O_3$ 0.9 wt%) as well as Al ($Al_2O_3$ 2.1 wt%) (GAZO) and ZnO doped only with Al ($Al_2O_3$ 3 wt%) (AZO). It was investigated how it affects the moisture resistance of the transparent electrode. In addition, $Cu(In,Ga)Se_2$ thin film solar cells with two transparent oxides as front electrodes were fabricated, and the correlation between humidity resistance of transparent electrodes and device performance of solar cells was examined. When both transparent electrodes were exposed to high temperature distilled water, they showed a rapid increase in sheet resistance and a decrease in the fill factor of the solar cell. However, AZO showed a drastic decrease in efficiency at the beginning of exposure, while GAZO showed that the deterioration of efficiency occurred over a long period of time and that the long term moisture resistance of GAZO was better.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1998년도 하계학술대회 논문집 D
• /
• pp.1264-1267
• /
• 1998

$Cu(In_xGa_{1-x})Se_2$ thin films were prepared and characterized with various Ga contents. As the Ga content increased, the grain size of CIGS film became smaller. The 2 $\theta$ values in XRD patterns were shifted to larger values and the overlapped peaks were splitted. The energy bandgap increased from 1.04 to 1.67 eV and the resistivity decreased. The solar cell fabricated with ZnO/CdS/$Cu(In_{0.7}Ga_{0.3})Se_2/Mo$ structure yielded an efficeincy of 14.48% with an acitive area of 0.18 $cm^2$. The efficiency decreased with further increase of Ga content.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.85.2-85.2
• /
• 2010

$Cu_2ZnSnSe_4$ (CZTSe) is one of candidate to alternate $Cu(In,Ga)Se_2$ as solar absorber material for solar cell. The expensive elements of In and Ga are replaced by Zn and Sn, respectively to lower the material cost. In this study we fabricated CZTSe thin film by selenization of single precursor layer consisted metallic constituent. Precursor compositions ratio were selected to have Cu-poor and Zn-rich content and prepared by RF magnetron sputtering. Thermal processing was applied to introduce selenium into as-deposited films at temperatures ranging from 350 to 500 for time up to 120 minutes. Single precursor films showed amorphous structure and consist of individual elements of Cu, Zn, and Sn. It was confirmed by XRD analysis that synthesis of CZTSe compound is occurred from lower temperature process, although concurrently additional phases such as binary cooper selenides are also existed. The quality of CZTSe crystal was improved as temperature increased. We also investigated the optical and electrical properties of as-selenized CZTSe as well.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
• /
• pp.386-391
• /
• 2003

Sing1e crystal $CuAlSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at $410^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$source at $680^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence(PL) and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $CuAlSe_2$ thin films measured with Hall effect by van der Pauw method are $9.24{\times}10^{16}\;cm^{-3}$ and $295\;cm^2/V{\cdot}\;s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;2.8382\;eV\;-\;(8.86\;{\times}\;10^{-4}\;eV/K)T^2/(T\;+\;155K)$. After the as-grown single crystal $CuAlSe_2$ thin films were annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of single crystal $CuAlSe_2$ thin films has been investigated by PL at 10 K. The native defects of $V_{Cd}$, $V_{Se}$, $Cd_{int}$, and $Se_{int}$ obtained by PL measurements were classified as donors or accepters. And we concluded that the heat-treatment in the Cu-atmosphere converted single crystal $CuAlSe_2$ thin films to an optical n-type. Also, we confirmed that Al in $CuAlSe_2/GaAs$ did not form the native defects because Al in single crystal $CuAlSe_2$ thin films existed in the form of stable bonds.

• 한국전기전자재료학회논문지
• /
• 제16권10호
• /
• pp.871-880
• /
• 2003

Single crystal CuAlSe$_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at 410 C with hot wall epitaxy (HWE) system by evaporating CuAlSe$_2$ source at 680 C. The crystalline structure of the single crystal thin films was investigated by the photoluminescence(PL) and double crystal X -ray diffraction (DCXD). The carrier density and mobility of single crystal CuAlSe$_2$ thin films measured with Hall effect by van der Pauw method are 9.24${\times}$10$\^$16/ cm$\^$-3/ and 295 cm$^2$/V $.$ s at 293 K, respectively. The temperature dependence of the energy band gap of the CuAlSe$_2$ obtained from the absorption spectra was well described by the Varshni's relation, Eg(T) = 2.8382 eV - (8.86 ${\times}$ 10$\^$-4/ eV/K)T$^2$/(T + 155K). After the as-grown single crystal CuAlSe$_2$ thin films were annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of single crystal CuAlSe$_2$ thin films has been investigated by PL at 10 K. The native defects of V$\_$cd/, V$\_$se/, Cd$\_$int/, and Se$\_$int/ obtained by PL measurements were classified as donors or acceptors. And we concluded that the heat-treatment in the Cu-atmosphere converted single crystal CuAlSe$_2$ thin films to an optical n-type. Also, we confirmed that Al in CuAlSe$_2$/GaAs did not form the native defects because Al in single crystal CuAlSe$_2$ thin films existed in the form of stable bonds.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.314.2-314.2
• /
• 2013

CIGS 박막의 물성은 조성에 크게 영향을 받으며, 특히 박막 내 Cu/(In+Ga) 비는 매우 중요한 변수로서 태양전지 특성에 영향을 주게 된다. Cu(In1-xGax)Se2 박막의 전하농도 및 반도체로의 성격을 가장 명확하게 결정하는 조성비는 Cu/(In+Ga) 비이다. 태양전지와 같은 소자로 작용하기 위해서는 Cu/(In+Ga) 비가 1보다 작아야 한다. 고효율의 태양전지는 Cu/(In+Ga)조성이 0.85~0.95로 slightly Cu-poor가 되어야 만들어진다. 본 연구에서는 Cu조성에 따른 CIGS 박막의 구조적, 전기적 특성과 CIGS 태양전지 효율 특성에 관하여 연구하였다. 미세구조 분석결과 Cu 조성이 증가함에 따라 큰 결정립을 가지며 결정립의 성장이 고르게 되어 접합 형성을 좋게 하는 경향을 보였다. X선 회절 분석결과, Cu 함유량 비율이 증가하면서 <112>의 우선배향성에서 <220/204>으로 변화하였다. 그러나, Cu/(In+Ga) 비율이 1이상이 첨가됨에 따라 우선배향은 다시 <112>로 변화함을 알 수 있었다. EDX 분석결과 Ga/(In+Ga) 0.31, Cu/(In+Ga) 0.86의 비율일 때, Carrier density $1.49{\times}1016$ cm-3을 나타내었다. CIGS의 태양전지의 효율 측정결과 Voc=596mV, Jsc=37.84mA/cm2, FF=72.96%로 ${\eta}$=16.47%를 달성하였다.

• Current Photovoltaic Research
• /
• 제3권1호
• /
• pp.16-20
• /
• 2015

Ag addition in chalcopyrite materials is known to lead beneficial changes in aspects of structural and electronic properties. In this work, the effects of Ag alloying of $Cu(In,Ga)Se_2$-based solar cells has been investigated. Wide bandgap $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x = 0.75~0.8) films have been deposited using a three-stage co-evaporation with various Ag/(Ag+Cu) ratios. With Ag alloying the $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x~0.8) films were found to have greater grainsize and film thickness. Device were also fabricated with the $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ (x~0.8) films and their J-V and quantum efficiency measurements were carried out. The highest-efficiency $(Ag,Cu)(In_{1-x},Ga_x)Se_2$ solar cell with Eg > 1.5 eV had an efficiency of 12.2% with device parameters $V_{OC}=0.810V$, $J_{SC}=21.7mA/cm^2$, and FF = 69.0%.

• 태양에너지
• /
• 제20권2호
• /
• pp.43-54
• /
• 2000

동시 진공증발법을 이용하여 coming glass, soda-lime glass, Mo가 증착된 soda-lime glass 위에 $Cu(In_{1-x}Ga_x)Se_2$ 박막을 증착하였다. Soda-lime glass 위에서 제조된 $Cu(In_{0.5}Ga_{0.5})Se_2$ 박막의 전기비저항값과 정공농도는Cu/(In+Ga)비에 큰 영향을 받지 않았다. Soda-lime glass위에서의 $Cu(In_{1-x}Ga_x)Se_2$ 박막내부와 표면에는 Na이 검출되었고, 표면의 Na는 산소와 결합하고 있었으며, Cu가 부족한 조성에서 이차상이 형성되었다. Ga/(In+Ga)비가 증가할수록 $Cu(In_{1-x}Ga_x)Se_2$ 박막은 회절 peak들의 큰 회절각으로 이동, 초격자 peak등의 분리, 결정립 크기의 감소가 관찰되었다. $Cu_{0.91}(In_{1-x}Ga_x)Se_2$ 박막은 Ga/(In+Ga)비에 무관하게 전기적으로 p-type을 나타내었다. Ag/n-ZnO /i-Zno/CdS/$Cu_{0.91}(In_{0.7}Ga_{0.3})Se_2$/Mo/glass구조의 태양전지를 제조하였으며, 태양전지변환효율(Eff.) = 14.48%, 단락전류밀도(Jsc) = $34.88mA/cm^2$, 개방전압(Voc) =581.5 mV, 충실도(F.F) = 0.714을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
• /
• pp.76-77
• /
• 2005

Single crystal $CuAlSe_2$ layers were grown on thoroughly etched semi-insulating GaAs(100) substrate at 410$^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$ source at $680^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence(PL) and double crystal X-ray diffraction (DCXO). The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorpt ion spectra was wel1 described by the Varshni's relation, $E_g$(T) = 2.8382 eV - ($8.86\times10^{-4}$ eV/H)$T_2$/(T + 155K). After the as-grown single crystal $CuAlSe_2$ thin films were annealed in Cu-, Se-, and Al-atmospheres, the origin of point defects of single crystal $CuAlSe_2$ thin films has been investigated by PL at 10 K. The native defects of $V_{cd}$, $V_{se}$, $Cd_{int}$, and $Se_{int}$ obtained by PL measurements were classified as donors or acceptors. And we concluded that the heat-treatment in the Cu-atmosphere converted single crystal $CuAlSe_2$ thin films to an optical n-type. Also. we confirmed that hi in $CuAlSe_2$/GaAs did not form the native defects because Al in single crystal $CuAlSe_2$ thin films existed in the form of stable bonds.