Fabrication of wide-bandgap β-Cu(In,Ga)<SUB>3</SUB>Se<SUB>5</SUB> thin films and their application to solar cells

Ji Hye Kim,Young Min Shin,Seung Tae Kim,HyukSang Kwon,Byung Tae Ahn 한국태양광발전학회 2013 Current Photovoltaic Research Vol.1 No.1

Cu(In,Ga)3Se5 is a candidate material for the top cell of Cu(In,Ga)Se2 tandem cells. This phase is often found at the surface of the Cu(In,Ga)Se2 film during Cu(In,Ga)Se2 cell fabrication, and plays a positive role in Cu(In,Ga)Se2 cell performance. However, the exact properties of the Cu(In,Ga)3Se5 film have not been extensively studied yet. In this work, Cu(In,Ga)3Se5 films were fabricated on Mocoated soda-lime glass substrates by a three-stage co-evaporation process. The Cu content in the film was controlled by varying the deposition time of each stage. X-ray diffraction and Raman spectroscopy analyses showed that, even though the stoichiometric Cu/(In+Ga) ratio is 0.25, Cu(In,Ga)3Se5 is easily formed in a wide range of Cu content as long as the Cu/(In+Ga) ratio is held below 0.5. The optical band gap of Cu0.3(In0.65Ga0.35)3Se5 composition was found to be 1.35eV. As the Cu/(In+Ga) ratio was decreased further below 0.5, the grain size became smaller and the band gap increased. Unlike the Cu(In,Ga)Se2 solar cell, an external supply of Na with Na2S deposition further increased the cell efficiency of the Cu(In,Ga)3Se5 solar cell, indicating that more Na is necessary, in addition to the Na supply from the soda lime glass, to suppress deep level defects in the Cu(In,Ga)3Se5 film. The cell efficiency of CdS/Cu(In,Ga)3Se5 was improved from 8.8 to 11.2% by incorporating Na with Na2S deposition on the CIGS film. The fill factor was significantly improved by the Na incorporation, due to a decrease of deep-level defects.

Cu₂In₃, CuGa, Cu₂Se를 이용한 전구체박막을 셀렌화하여 제조한 Cu(In,Ga)Se₂ 박막의 미세구조 및 농도분포 변화

이종철,정광선,안병태,Lee, Jong-Chul,Jung, Gwang-Sun,Ahn, Byung-Tae 한국재료학회 2011 한국재료학회지 Vol.21 No.10

A high-quality CIGS film with a selenization process needs to be developed for low-cost and large-scale production. In this study, we used $Cu_2In_3$, CuGa and $Cu_2Se$ sputter targets for the deposition of a precursor. The precursor deposited by sputtering was selenized in Se vapor. The precursor layer deposited by the co-sputtering of $Cu_2In_3$, CuGa and $Cu_2Se$ showed a uniform distribution of Cu, In, Ga, and Se throughout the layer with Cu, In, CuIn, CuGa and $Cu_2Se$ phases. After selenization at $550^{\circ}C$ for 30 min, the CIGS film showed a double-layer microstructure with a large-grained top layer and a small-grained bottom layer. In the AES depth profile, In was found to have accumulated near the surface while Cu had accumulated in the middle of the CIGS film. By adding a Cu-In-Ga interlayer between the co-sputtered precursor layer and the Mo film and adding a thin $Cu_2Se$ layer onto the co-sputtered precursor layer, large CIGS grains throughout the film were produced. However, the Cu accumulated in the middle of CIGS film in this case as well. By supplying In, Ga and Se to the CIGS film, a uniform distribution of Cu, In, Ga and Se was achieved in the middle of the CIGS film.

Fabrication of wide-bandgap β-Cu(In,Ga)₃Se₅ thin films and their application to solar cells

Kim, Ji Hye,Shin, Young Min,Kim, Seung Tae,Kwon, HyukSang,Ahn, Byung Tae Korea Photovoltaic Society 2013 Current Photovoltaic Research Vol.1 No.1

$Cu(In,Ga)_3Se_5$ is a candidate material for the top cell of $Cu(In,Ga)Se_2$ tandem cells. This phase is often found at the surface of the $Cu(In,Ga)Se_2$ film during $Cu(In,Ga)Se_2$ cell fabrication, and plays a positive role in $Cu(In,Ga)Se_2$ cell performance. However, the exact properties of the $Cu(In,Ga)_3Se_5$ film have not been extensively studied yet. In this work, $Cu(In,Ga)_3Se_5$ films were fabricated on Mo-coated soda-lime glass substrates by a three-stage co-evaporation process. The Cu content in the film was controlled by varying the deposition time of each stage. X-ray diffraction and Raman spectroscopy analyses showed that, even though the stoichiometric Cu/(In+Ga) ratio is 0.25, $Cu(In,Ga)_3Se_5$ is easily formed in a wide range of Cu content as long as the Cu/(In+Ga) ratio is held below 0.5. The optical band gap of $Cu_{0.3}(In_{0.65}Ga_{0.35})_3Se_5$ composition was found to be 1.35eV. As the Cu/(In+Ga) ratio was decreased further below 0.5, the grain size became smaller and the band gap increased. Unlike the $Cu(In,Ga)Se_2$ solar cell, an external supply of Na with $Na_2S$ deposition further increased the cell efficiency of the $Cu(In,Ga)_3Se_5$ solar cell, indicating that more Na is necessary, in addition to the Na supply from the soda lime glass, to suppress deep level defects in the $Cu(In,Ga)_3Se_5$ film. The cell efficiency of $CdS/Cu(In,Ga)_3Se_5$ was improved from 8.8 to 11.2% by incorporating Na with $Na_2S$ deposition on the CIGS film. The fill factor was significantly improved by the Na incorporation, due to a decrease of deep-level defects.

Effect of the Cu Bottom Layer on the Optical and Electrical Properties of In₂O₃/Cu Thin Films

Daeil Kim(김대일) 한국진공학회(ASCT) 2011 Applied Science and Convergence Technology Vol.20 No.5

유리 기판 위에 RF와 DC 마그네트론 스퍼터링 방법으로 100 ㎚ 두께의 In₂O₃ 단층 박막과 In₂O₃ 100 ㎚/Cu 3 ㎚의 두께를 갖는 적층박막을 증착하고, 구리 기저 층 증착에 따른 상부 In₂O₃ 박막의 광학적, 전기적 특성의 변화를 연구하였다. 상온에서 증착 된 In₂O₃ 박막의 가시광 투과도와 면 저항은 79%와 2,300 Ω/□이었다. 구리 기저 층의 광 흡수에 의하여, In₂O₃/Cu 적 층박막의 가시광 투과도는 71%로 감소하였으나, 면 저항은 110 Ω/□로 측정되어 상대적으로 우수한 전기적 특성을 구할 수 있었다. 본 연구에서 Figure of Merit 분석을 통하여 구리 기저 층이 상부 In₂O₃ 투명전극의 전기적, 광학적 특성을 개선 할 수 있음을 확인하였다. Indium oxide (In₂O₃) single layer and In₂O₃/copper (Cu) bi-layer films were prepared on glass substrates by RF and DC magnetron sputtering without intentional substrate heating. In order to determine the effect of the Cu bottom layer on the optical, electrical and structural properties of In₂O₃ films, 3-㎚-thick Cu film was deposited on the glass substrate prior to deposition of the In₂O₃ films. As-deposited In2O3 films had an optical transmittance of 79% in the visible wavelength region and a sheet resistance of 2,300 Ω/□, while the In₂O₃/Cu film had optical and electrical properties that were influenced by the Cu bottom layer. In₂O₃/Cu films had a lower sheet resistance of 110 Ω/□ and an optical transmittance of 71%. Based on the figure of merit, it can be concluded that the Cu bottom layer effectively increases the performance of In2O3 films for use as transparent conducting oxides in flexible display applications.

Warm Spray 공정과 Cu-Ga 및 Cu-In 혼합 분말을 이용한 CGI계 복합 코팅층의 제조 및 특성

전민광,이명주,김형준,이기안,Jeon, Min-Gwang,Lee, Myeong-Ju,Kim, Hyeong-Jun,Lee, Kee-Ahn 한국분말야금학회 2014 한국분말재료학회지 (KPMI) Vol.21 No.3

This study manufactured a CIG-based composite coating layer utilizing a new warm spray process, and a mixed powder of Cu-20at.%Ga and Cu-20at.%In. In order to obtain the mixed powder with desired composition, the Cu-20at.%Ga and Cu-20at.%In powders were mixed with a 7:1 ratio. The mixed powder had an average particle size of $35.4{\mu}m$. Through the utilization of a warm spray process, a CIG-based composite coating layer of $180{\mu}m$ thickness could be manufactured on a pure Al matrix. To analyze the microstructure and phase, the warm sprayed coating layer underwent XRD, SEM/EDS and EMPA analyses. In addition, to improve the physical properties of the coating layer, an annealing heat treatment was conducted at temperatures of $200^{\circ}C$, $400^{\circ}C$ and $600^{\circ}C$ for 1 hour each. The microstructure analysis identified ${\alpha}$-Cu, $Cu_4In$ and $Cu_3Ga$ phases in the early mixed powder, while $Cu_4In$ disappeared, and additional $Cu_9In_4$ and $Cu_9Ga_4$ phases were identified in the warm sprayed coating layer. Porosity after annealing heat treatment reduced from 0.75% (warm sprayed coating layer) to 0.6% (after $600^{\circ}C/1hr$. heat treatment), and hardness reduced from 288 Hv to 190 Hv. No significant phase changes were found after annealing heat treatment.

Effects of Cu/In Compositional Ratio on the Characteristics of CuInS2 Absorber Layers Prepared by Sulfurization of Metallic Precursors

Seung Hwan Lee,신승욱,Jun Hee Han,이정용,Myeong Gil Kang,G. L. Agawane,Jae Ho Yun,Jong Ha Moon,Jin Hyeok Kim 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.2

This paper investigates the effects of the Cu/In compositional ratio on morphological, structural and optical properties of CuInS2 (CIS) absorber layers formed by sulfurization of In/Cu stacked precursors. In/Cu stacked precursors were prepared on Mo-coated soda-lime glass substrates by DC magnetron sputtering method. The Cu/In compositional ratio in the precursor thin film was varied from 0.55 to 1.44. The as-deposited stacked precursor thin films were sulfurized using a tubular furnace annealing system in a mixture of N2 (95%) +H2S (5%) atmosphere at 450°C for 1 hour. X-ray diffraction patterns and Raman spectra results showed that the sulfurized thin films contained both tetragonal CIS and a Cu-based secondary phase, except for the film with a Cu/In compositional ratio of 0.55. Field emission-scanning electron microscopy study showed that the microstructure of the sulfurized CIS thin films became denser with increasing Cu/In compositional ratio. Optical properties of the CIS thin films showed that all the CIS thin films had a good absorption coefficient over 104cm−1in the visible region. The direct band gap energy of the sulfurized CIS thin films decreased from 1.39 eV to 1.08 eV with increasing Cu/In compositional ratio. These results demonstrated the effect of the Cu/In compositional ratio on the properties of the CIS thin films and the consequent importance of precisely controlling the metal ratio in the precursor film in order to control the properties of absorber layers in thin film solar cells.

Control of Point Defects in the Cu(In,Ga)Se2 Film Synthesized at Low Temperature from a Cu/In2Se3 Stacked Precursor

정광선,김승태,고영민,문선홍,최용우,안병태 대한금속·재료학회 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.4

Low-temperature fabrication of Cu(In,Ga)Se2 (CIGS) film is essential forflexible CIGS solar cells. A large-grained CIGS film was synthesized with aSe-deficient Cu/In,Ga)2Se3 stacked precursor by reacting at 500 °C in avacuum and was then subsequently annealing in Se environment. The CIGSsolar cell with the as-prepared CIGS film had a poor cell performance due toa very low Ga composition at the CIGS surface. The surface Ga compositionwas controlled to 0.2 by supplying In, Ga, and Se in a temperature range of350 to 500 °C. From an analysis of the photoluminescence spectra, we foundthat the point defects, Se vacancy and In-in-Cu antisite, in the CIGS filmwere greatly reduced by annealing below 450 °C. The short-circuit currentwas pronouncedly increased in the CIGS cells. The open-circuit voltagedepended on both the Ga composition and Cu composition at the CIGSsurface. In particular, a low Cu composition at the CIGS surface was essentialfor the higher performance solar cells. Our results indicated that CIGSs filmsynthesized at high temperature must be annealed at 350 °C or below toreduce undesirable point defects.

The in-situ TEM isothermal aging evolution in a μ-Cu/NiAu/Sn/Cu solder joint for full intermetallic compounds interconnects of flexible electronics

Jinhong Liu,Xinyi Jing,Jieshi Chen,Kyung‑Wook Paik,Peng He,Shuye Zhang 대한금속·재료학회 2024 ELECTRONIC MATERIALS LETTERS Vol.20 No.3

A structure composed of various Cu–Ni–Sn IMCs would develop from severe Joule heat and excessive elemental diff usionunder high-density current in the solder joints of fl exible printed circuit (FPC). Herein, we fi rstly observed the evolution ofa Cu 6 Sn 5 + Cu 3 Sn/(Ni,Cu) 3 Sn 4 hybrid structure in a μ-Cu/NiAu/Sn/Cu solder joint for full intermetallic compounds (IMCs)interconnect of fl exible electronics under isothermal aging condition by in-situ TEM. The joint was divided into two regions,the IMC type on the right region remained unchanged with dwell time prolonging, while the ratio of Cu 3 Sn on the left regionat various dwell times fi tted the JMAK model when the kinetic parameter n picked 1.5, indicating that grain boundary diff usionwas the predominant mechanism for transporting Cu atoms. The nucleation and growth of Cu 3 Sn grains were fi nishedin the Cu 6 Sn 5 layer. The nucleation of a Cu 3 Sn grain with a spherical cap shape was fi rstly captured by HRTEM, and Cu 3 Sngrains underwent a transformation from columnar to equiaxed when the dwell time was increased, making the morphologyof Cu 3 Sn grains in a μ-Cu/NiAu/Sn/Cu solder joint signifi cantly diff erent from the situation in larger solder joints. This studyis expected to provide an in-depth study of the microstructural evolution of micro Cu/NiAu/Sn/Cu solder joints under agingcondition and thereby expand their application in the microelectronic industry.

Bi-Sb-Te계 합금의 열전물성에 대한 Cu 및 In 첨가 영향

조현준,김현식,김상일 대한금속·재료학회 2019 대한금속·재료학회지 Vol.57 No.10

Herein we report the effect of Cu/In doping on the electronic and thermal transport properties of Bi-Sb-Te thermoelectric alloys. To closely examine the role of each doping element when incorporated in a Bi0.4Sb1.6Te3 alloy, different groups of samples were prepared and characterized, including undoped Bi0.4Sb1.6Te3, In single-doped samples and In and Cu doped ones. It was observed that Cu and In had different impacts on the thermoelectric properties of the Bi0.4Sb1.6Te3. For example, the Hall carrier concentration of Bi0.4Sb1.6Te3 was increased by Cu doping and decreased by In doping while maintaining Hall mobility, which suggests that the physical parameters related to the thermoelectric transport can be carefully controlled by doping with Cu and In. In addition, we found that the electronic structure of Bi0.4Sb1.6Te3 can be modified by Cu/In doping. The density of states effective mass (m * ) value of the Cu-doped sample (1.09 m0) was increased. However, the m * of the In-doped sample (0.85 m0) was decreased compared to the pristine sample (0.97 m0). Cu single-doped Bi0.4Sb1.6Te3 exhibited the maximum thermoelectric figure-of-merit because of the complexity of substitutional doping on Bi/Sb sites. Our results indicate that to enhance the performance of thermoelectric materials by doping with more than one element a well-designed doping strategy is required.

질화 규소 접합체의 미세구조와 파괴 강도에 관한 연구

차재철,강신후,박상환 한국세라믹학회 1999 한국세라믹학회지 Vol.36 No.8

본 연구에서는 Ag-Cu-Ti 와 Ag-Cu-In-Ti 를 사용하여 브레이징법으로 질화규소 간 접합체를 제작하고 $400^{\circ}C$와 $650^{\circ}C$에서 장시간(2000 h) 열처리 후 파괴 강도의 변화를 살펴보았다. 접합후 강도는 Ag-Cu-Ti 가 높게 나왔지만, 열처리 시간이 증가할수록 Ag-Cu-In-Ti 의 경우가 강도의 감소 정도가 작은 것으로 나타났다. 또한 고온 응용을 위해 개발된 새로운 접학 합금인 Au-Ni-Cr-Mo-Fe 계를 이용하여 질화 규소 간의 접합체를 제작하여 $650^{\circ}C$에서 100시간까지 장시간 열처리 하였다 접합 당시의 강도는 상용 접합 합금보다는 낮은 값을 보였지만, 열처리를 함에 따라 강도의 증가를 보였다 SUS316과의 접합시에는 중간재로 몰리브데늄 또는 구리를 사용하였으며 $400^{\circ}C$에서 1000시간 동안 열처리하였다. 강도는 몰리브데늄을 사용한 경우가 높게 나왔지만, 접합체의 형성이 어렵다는 단점이 있었다. 산화 실험에서는 Ti가 첨가된 접합 합금인 Ag-Cu-Ti 의 경우가 첨가되지 않은 Ag-Cu의 경우보다 산화가 잘 일어나며, 인듐을 첨가한 Ag-Cu-In-Ti 의 경우는 산화 억제의 효과가 나타났다. 전반적으로 In을 포함한 접합 합금이 고온 신뢰도 면에서 우수한 것으로 나타났다. Si3N4 -Si3N4 joints were made using Ag-Cu-Ti and Ag-Cu-In-Ti via brazing method and the change in joint strength was investigated after heat treatment at $400^{\circ}C$ or $650^{\circ}C$ for up to 2000h. The initial strength of as-brazed joints with Ag-Cu-In-Ti was lower but the reduction of the strength was less dramatic than that with Ag-Cu-Ti. The joints made of a new brazing alloy Au-Ni-Cr-Mo-Fe which is developed for high temperature applications were heat-treated at $650^{\circ}C$ for 1000h. As the heat treatment time increased the bond strength increased. The results of the joining system with Mo or Cu interlayer showed that the strength of the joint with Mo interlayer was higher but the system incurred problems in joint production Also it was found from oxidation experiment that Ti and In affected the oxidation resistance of brazing alloy.