Preferred Orientation Control of Cu(In1-xGax)Se2(x≈0.28) Thin Films and Its Influence on Solar Cell Characteristics

Chaisitsak, Sutichai; Yamada, Akira; Konagai, Makoto

doi:10.1143/jjap.41.507

Cited by 138 publications

(84 citation statements)

References 4 publications

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“…The assumption that there are orientation dependent differences in diffusion properties of Cd in CIGSe as suggested in Ref. 36 provides an explanation for the inhomogeneities. An electronic band diagram of the model we suggest is displayed in Figure 14.…”

Section: Ebic Kinkmentioning

confidence: 95%

Generation-dependent charge carrier transport in Cu(In,Ga)Se2/CdS/ZnO thin-film solar-cells

Nichterwitz

Caballero

Kaufmann

et al. 2013

Journal of Applied Physics

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Cross section electron-beam induced current (EBIC) and illumination-dependent current voltage (IV) measurements show that charge carrier transport in Cu(In,Ga)Se2 (CIGSe)/CdS/ZnO solar-cells is generation-dependent. We perform a detailed analysis of CIGSe solar cells with different CdS layer thicknesses and varying Ga-content in the absorber layer. In conjunction with numerical simulations, EBIC and IV data are used to develop a consistent model for charge and defect distributions with a focus on the heterojunction region. The best model to explain our experimental data is based on a p+ layer at the CIGSe/CdS interface leading to generation-dependent transport in EBIC at room temperature. Acceptor-type defect states at the CdS/ZnO interface cause a significant reduction of the photocurrent in the red-light illuminated IV characteristics at low temperatures (red kink effect). Shallow donor-type defect states at the p+ layer/CdS interface of some grains of the absorber layer are responsible for grain specific, i.e., spatially inhomogeneous, charge carrier transport observed in EBIC.

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Section: Ebic Kinkmentioning

confidence: 95%

Generation-dependent charge carrier transport in Cu(In,Ga)Se2/CdS/ZnO thin-film solar-cells

Nichterwitz

Caballero

Kaufmann

et al. 2013

Journal of Applied Physics

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“…The observed fill factor effect is in accordance to the model of Chaisitsak. By favoring a 220/204 orientation a higher background-pressure seems to have a similar effect as a low selenium to In/Ga flux ratio in the first stage of the process [3]- [4].…”

Section: Effect On Absorber Propertiesmentioning

confidence: 97%

“…5). According to the model of Chaisitsak et al [3] a 220/204 orientation is favorable, because Cd atoms can better bond/penetrate into the CIGSe surface during CdS chemical bath deposition of the buffer layer and a higher FF can be achieved. Compared to a randomly oriented CISe powder (JCPDS card 01-081-1936) we measure slightly {220}/{204} preferentially orientated grains for three of the four samples.…”

Section: Effect On Absorber Propertiesmentioning

confidence: 99%

Influence of residual gas composition and background pressure in a multi-stage co-evaporation chamber on the quality of Cu(In, Ga)Se<inf>2</inf> thin films and their device performance

Greiner

Lauche

Heinemann

et al. 2016

2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC)

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-Thin film solar cells with Cu(In,Ga)Se 2 (CIGSe) absorbers prepared by co-evaporation reach efficiencies above 21% [1]. Typical multi-stage co-evaporation chambers are MBElike (ultra-)high vacuum systems with individual effusion sources for each element. Cleanliness of the process chamber and the background pressure during the co-evaporation process could be of importance for the chamber design and a fair comparison of production costs when comparing different PV/Chalcopyrite technologies.Here we study the influence of the background pressure quality on the electronic and structural properties of the deposited absorber layer. To achieve this, we analyzed the residual gas composition before and the background pressure during consecutive co-evaporation processes and investigate the effect of a combined cleaning (mechanical and electro-chemical) of the chamber walls together with a simple conditioning of the chamber after opening the chamber and re-filling the crucibles.Cleaning of the chamber yielded a significant reduction in carbon species and an overall lower base pressure. The background pressure during the process was reduced from ~6*10 -6 mbar (before cleaning with water cooling shroud) to 1*10 -7 mbar (after cleaning with LN 2 filled cooling shroud). The type and amounts of contaminants in the absorber layer are characterized by laser ablation inductively coupled plasma mass spectroscopy (LA ICP-MS). The impact of the process pressure on the growth of the CIGSe layer is analyzed with respect to preferential orientation (using XRD), grain-size (using SEM), in-depth elemental gradients (using GDOES) and the electronic quality (using TRPL, C-V). Analysis of completed solar cell devices shows that the absorber band-gap is hardly affected by the chamber conditions, whereas we see an improved collection of charge carriers generated by photons in the infra-red spectral range from the conditioned chamber, also resulting in slightly higher j sc . The major effect is an increase in median V oc values from 585mV (before cleaning and conditioning) to 635mV (after cleaning and condition). The overall solar cell efficiency is increased by 18% (relative).

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“…Deposition of thin CdS films from aqueous solutions is a reaction between cadmium salt and thiocarbamid (thiourea) in alkaline medium. Mostly are used simple cadmium salts: CdSO 4 (Chaisitsak at al., 2002, Contreras at al., 2002, Tiwari & Tiwari, 2006, Chen at al., 2008, CdI 2 (Nakada & Kunioka, 1999, Hashimoto at al., 1998, Cd(CH3COO) 2 (Granath at al., 2000, Rau & Scmidt, 2001) and CdCl 2 (Qiu at al., 1997, Aguilar-Hernández at al., 2006). Thiourea (TM) is used as sulfide agent in the reactions of sulfide deposition, as has a high affinity to metal cations and decomposes at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Chemical Surface Deposition of CdS Ultra Thin Films from Aqueous Solutions

Ільчук¹,

Shapoval²,

Kus’nézh³

2011

Solar Cells - Thin-Film Technologies

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Preferred Orientation Control of Cu(In_1-xGa_x)Se₂(x≈0.28) Thin Films and Its Influence on Solar Cell Characteristics

Cited by 138 publications

References 4 publications

Generation-dependent charge carrier transport in Cu(In,Ga)Se2/CdS/ZnO thin-film solar-cells

Generation-dependent charge carrier transport in Cu(In,Ga)Se2/CdS/ZnO thin-film solar-cells

Influence of residual gas composition and background pressure in a multi-stage co-evaporation chamber on the quality of Cu(In, Ga)Se<inf>2</inf> thin films and their device performance

Chemical Surface Deposition of CdS Ultra Thin Films from Aqueous Solutions

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