• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.19-22
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• 2009

A non-vacuum process for fabrication of $CuIn_xGa_{1-x}Se_2$ (CIGS) absorber layer from the corresponing Cu, In, Ga solution precursors was described. Cu, In, Ga precursor solution was prepared by a room temperature colloidal route by reacting the starting materials $Cu(NO_3)_2$, $InCl_3$, $Ga(NO_3)$ and methanol. The Cu, In, Ga precursor solution was mixed with ethylcellulose as organic binder material for the rheology of the mixture to be adjusted for the doctor blade method. After depositing the mixture of Cu, In, Ga solution with binder on Mo/glass substrate, the samples were preheated on the hot plate in air to evaporate remaining solvents and to burn the organic binder material. Subsequently, the resultant CIG/Mo/glass sample was selenized in Se evaporation in order to get a solar cell applicable dense CIGS absorber layer. The CIGS absorber layer selenized at $530^{\circ}C$ substrate temperature for 1h with various metal organic ratio.

• Transactions on Electrical and Electronic Materials
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• 제6권5호
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• pp.229-232
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• 2005

Direct characterization of band alignment at chemical bath deposition $(CBD)-CdS/Cu_{0.93}(In_{1-x}Ga_x)Se_2$ has been carried out by photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). Ar ion beam etching at the condition of the low ion kinetic energy of 400 eV yields a removal of surface contamination as well as successful development of intrinsic feature of each layer and the interfaces. Especially interior regions of the wide gap CIGS layers with a band gap of $1.4\~1.6\;eV$ were successfully exposed. IPES spectra revealed that conduction band offset (CBO) at the interface region over the wide gap CIGS of x = 0.60 and 0.75 was negative, where the conduction band minimum of CdS was lower than that of CIGS. It was also observed that an energy spacing between conduction band minimum (CBM) of CdS layer and valance band maximum (VBM) of $Cu_{0.93}(In_{0.25}Ga_{0.75})Se_2$ layer at interface region was no wider than that of the interface over the $Cu_{0.93}(In_{0.60}Ga_{0.40})Se_2$ layer.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.382-382
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• 2012

CIGS thin films have received great attention as a promising material for solar cells due to their high absorption coefficient, appropriate bandgap, long-term stability, and low cost production. CIGS thin films are deposited by various methods such as co-evaporation, sputtering, spray pyrolysis and electro-deposition. The deposition technique is one of the most important processes in preparing CIGS thin film solar cells. Among these methods, co-evaporation is one of the best technique for obtaining high quality and stoichiometric CIGS films. However, co-evaporation method is known to be unsuitable for commercialization. The sputtering is known to be very effective and feasible process for mass production. In this study, CIGS thin films have prepared by rf magnetron sputtering using a $Cu(In_{1-x}Ga_x)Se_2$ single quaternary target without post deposition selenization. This process has been examined by the effects of deposition parameters on the structural and compositional properties of the films. In addition, we will explore the influences of substrate temperature and additional annealing treatment after deposition on the characteristics of CIGS thin films. The thickness of CIGS films will be measured by Tencor-P1 profiler. The crystalline properties and surface morphology of the films will be analyzed using X-ray diffraction and scanning electron microscopy, respectively. The optical properties of the films will be determined by UV-Visible spectroscopy. Electrical properties of the films will be measured using van der Pauw geometry and Hall effect measurement at room temperature using indium ohmic contacts.

• 한국전기전자재료학회논문지
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• 제24권9호
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• pp.755-759
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• 2011

$Cu(In_{1-x},Ga_x)Se_2$ thin films have been considered as an effective absorber material for high efficient solar cells. In this paper, the CIGS thin films with varied Ga content were prepared using a co-evaporation process of three stage. We carry out structure and electrical optical property on the thin film in varied Ga content. CIGS thin films have been characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), energy-dispersive spectroscopy(EDS), four-point probe measurement, and the Hall measurement. To optimize Ga contents, Ga/(In+Ga) ratio were changed from 0.13 to 0.72. At this time the carrier concentrations were varied from $1.22{\times}10^{11}\;cm^{-3}$ to $5.07{\times}10^{16}\;cm^{-3}$, and electrical resistivity were varied from $1.11{\times}10^0\;{\Omega}-cm$ to $1.08{\times}10^2\;{\Omega}-cm$. A strong <220/204> orientation and a lager grain size were obtained at a Ga/(In+Ga) of 0.3. We were able to achieve conversion efficiency as high as 15.95% with a Ga/(In+Ga) of 0.3.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.383-386
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• 2002

Polycrystalline Cu(In,Ga)Se$_2$(CIGS) thin-films were grown by co-evaporation on a soda lime glass substrate. In this paper the effects of the Se evaporation temperature on the properties of CuIn0.75Ga0.25Se2 (CIGS) thin films. Structure, surface morphology and optical properties of CIGS thin films deposited at various Se evaporation temperatures have been investigated using a number of analysis techniques. X-ray diffraction (XRD) analysis shows that CIGS films exhibit a strong <112> preferred orientation. As expected, at higher Se evaporation temperatures the films displayed a lower degree of crystallinity. The <112> peak was also enhanced and other CIGS peaks appeared simultaneously. These results were supported by experimental work using scanning electron microscopy When the Se evaporation temperature was increased, the average grain size also decreased together with a reduction Cu content. The Se evaporation temperature also had a significant inf1uence on the transmission spectra. Increasing the Se evaporation temperature, the cell efficiency was improved dramatically to 11.75% with Voc = 556 mV, Jsc = 32.17 mA/cm2 and FF = 0.66. The Se evaporation temperature is an important parameter in thin film deposition regardless of the deposition technique being used to deposit thin films

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.296-296
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• 2011

동시 증발법(co-evaporation)에 의해 성장된 $CuIn_xGa_{1-x}Se_2$ (CIGS) 박막의 광학적 특성을 photoreflectance (PR) 분광법으로 연구하였다. 조성비 x는 0~1까지 변화시켰다. 시료의 두께는 약 2.2 ${\mu}m$였다. PR 측정은 변조빔 세기, 변조빔 주파수 및 온도의 함수로 조사하였다. PR 스펙트럼으로부터 조성비 x가 증가함에따라 시료의 띠간격 에너지가 증가하는 것을 관측하였다. 상온 PR 스펙트럼으로부터 시료내에 형성된 내부 전기장을 구하였다. 그리고 변조빔 세기의 증가에 따른 PR 신호의 세기는 점차 증가하는 반면에, 변조 주파수를 증가시킴에 따라 신호의 세기가 점차 감소함을 보였다. PR 신호의 온도 의존성 실험으로부터 띠간격 에너지의 변화 및 Varshni 계수 등을 구하여 CIGS 시료의 특성을 조사하였다.

• 한국재료학회지
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• 제21권8호
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• pp.461-467
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• 2011

Cu(In, Ga)$Se_2$ (CIGS) precursor films were electrodeposited on Mo/glass substrates in acidic solutions containing $Cu^{2+}$, $In^{3+}$, $Ga^{3+}$, and $Se^{4+}$ ions at -0.6 V (SCE) and pH. 1.8. In order to induce recrystallization, the electrodeposited $Cu_{1.00}In_{0.81}Ga_{0.09}Se_{2.08}$ (25.0 at.% Cu + 20.2 at.% In + 2.2 at.% Ga + 52.0 at.% Se) precursor films were annealed under a high Se gas atmosphere for 15, 30, 45, and 60 min, respectively, at $500^{\circ}C$. The Se amount in the film increased from 52 at.% to 62 at.%, whereas the In amount in the film decreased from 20.8 at.% to 9.1 at.% as the annealing time increased from 0 (asdeposited state) to 60 min. These results were attributed to the Se introduced from the furnace atmosphere and reacted with the In present in the precursor films, resulting in the formation of the volatile $In_2Se$. CIGS precursor grains with a cauliflower shape grew as larger grains with the $CuSe_2$ and/or $Cu_{2-x}Se$ faceted phases as the annealing times increased. These faceted phases resulted in rough surface morphologies of the CIGS films. Furthermore, the CIGS layers were not dense because the empty spaces between the grains were not removed via annealing. Uniform thicknesses of the $MoSe_2$ layers occurred at the 45 and 60 min annealing time. This implies that there was a stable reaction between the Mo back electrode and the Se diffused through the CIGS film. The results obtained in the present research were sufficiently different from comparable studies where the recrystallization annealing was performed under an atmosphere of Ar gas only or a low Se gas pressure.

• 한국결정성장학회지
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• 제20권3호
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• pp.107-112
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• 2010

높은 광흡수 계수를$(1{\times}10^5cm^{-1})$ 가지는 CIGS는 Ga의 비율에 따라서 밴드갭을 조절할 수 있다는 장점을 지니고 있다. CIGS의 밴드갭은 Ga의 비율에 따라 $CuInSe_2$(Eg: 1.0 eV)에서 $CuGaSe_2$(Eg: 1.68 eV)까지의 범위에 존재하며, 태양전지에 서 이상적인 fill factor 모양을 가지도록 Ga의 비율을 높게 조성한다. CIGS 흡수층을 제작하는 방법에는 co-evaporator 방식이 가장 널리 사용되며 연구되고 있다. 이에 본 연구에서는 수평 형태의 hydride vapor transport (HVT)법을 고안하여 CIGS 나노 구조 및 에피성장을 시도하였다. HVT법은 $N_2$ 분위기에서 원료부의 CIGS 혼합물을 HCl과 반응시켜 염화물 기체상태로 변환 후 growth zone까지 이동하여 성장을 하는 방식이다. 성장기판은 c-$Al_2O_3$ 기판과 u-GaN을 사용하였다. 성장 후 field emission scanning electron microscopy(FE-SEM)과 energy dispersive spectrometer(EDS)를 이용하여 관찰하였다.

• 한국전기전자재료학회논문지
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• 제27권4호
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• pp.203-208
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• 2014

In this study, Sputtering method was used to grow Al-dopes ZnO films on a CIGS absorber layer, in order to examine the effect of TCO on properties of CIGS solar cell devices. Structural, electrical and optical properties were investigated by varied thickness of Al-dopes ZnO films. Also, relation to the application as a window layer in CIGS thin film solar cell were studied. It was found that the electrical and structural properties of ZnO:Al film improved with increasing its thickness. However, the optical properties degraded. Jsc of the fabricated CIGS based solar cells was significantly influenced by the variation of the ZnO:Al window layer thickness. Because ZnO:Al window layer is one of the Rs factors in CIGS solar cell. Rs has the biggest influence on efficiency characteristic. In order to obtain high efficiency of CIGS solar cell, ZnO:Al window layer should be fabricated with electrically and optically optimized.

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