Investigation of high-quality CuInSe2 films with various Cu/In ratios

Ko, Hang-Ju; Lee, Gyoung-Hoon; Kim, Hyojin; Han, Myoung-Soo; Jeong, Chaehwan; Lee, Jong-Ho; Kim, Ho‐Sung; Kim, Jin-Hyeok; Kim, Kwang‐Bok; Lee, Sukho

doi:10.1016/j.jcrysgro.2011.02.043

Cited by 11 publications

(4 citation statements)

References 9 publications

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“…The higher r and lower N p for Cu-poor films can be attributed to the absence of metal-like Cu 2 À x Se phase. However, the N p of stoichiometric Cu-poor films is evidently higher than the CIGS films, which show N p of 10 16 -10 17 cm À 3 [39,40]. Furthermore, with Mo back contact below the p-type CIGS also attributed to the higher N p and low r.…”

Section: Electrical Studymentioning

confidence: 94%

A study on composition, structure and optical properties of copper-poor CIGS thin film deposited by sequential sputtering of CuGa/In and In/(CuGa+In) precursors

Park

Sharma

Ashok

et al. 2012

Journal of Crystal Growth

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Section: Electrical Studymentioning

confidence: 94%

A study on composition, structure and optical properties of copper-poor CIGS thin film deposited by sequential sputtering of CuGa/In and In/(CuGa+In) precursors

Park

Sharma

Ashok

et al. 2012

Journal of Crystal Growth

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“…With respect to non-stoichiometry, earlier studies only agree that nominally Cu-rich CuInSe 2 (Cu:In > 1 during the growth process) grown or annealed under Se excess is always p-type, while for all other combinations of Cu and Se conditions both n-and p-type samples are reported by different authors. [2][3][4][5][6][7] Furthermore, the net doping in p-type samples was found to decrease with lower Cu:In ratios. 2,6 However, the highly p-conducting copper selenide secondary phase observed under Cu-rich growth conditions had not been etched in these studies, and hence will be at least partly responsible for the observed p-type doping of Cu-rich samples.…”

Section: Introductionmentioning

confidence: 90%

Doping mechanism in pure CuInSe2

Werner

Colombara

Melchiorre

et al. 2016

Journal of Applied Physics

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We investigate the dopant concentration and majority carrier mobility in epitaxial CuInSe 2 thin films for different copper-to-indium ratios and selenium excess during growth. We find that all copper-poor samples are n-type, and that hopping conduction in a shallow donor state plays a significant role for carrier transport. Annealing in sodium ambient enhances gallium in-diffusion from the substrate wafer and changes the net doping of the previously n-type samples to p-type. We suggest that sodium incorporation from the glass might be responsible for the observed p-type doping in polycrystalline Cu-poor CuInSe 2 solar cell absorbers. Published by AIP Publishing.

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“…Increasing the Cu content toward stoichiometry can considerably reduce the presence of such defects and defect complexes. It has been shown that stoichiometric Cu concentrations can be beneficial for absorber crystallinity, defect density, mobility, and doping density . Despite this, solar cells based on Cu stoichiometric CuInSe 2 (CIS) have never reached efficiencies above 13.5%, while Cu‐deficient CIS yielded efficiencies only up to 15.0% .…”

Section: Introductionmentioning

confidence: 99%

Efficiency Improvement of Near‐Stoichiometric CuInSe₂ Solar Cells for Application in Tandem Devices

Feurer

Carron

Sevilla

et al. 2019

Advanced Energy Materials

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the formation of defect complexes and possibly even phases of ordered defect compounds. [9][10][11][12] Increasing the Cu content toward stoi chiometry can considerably reduce the pre sence of such defects and defect complexes. It has been shown that stoichiometric Cu concentrations can be beneficial for absorber crystallinity, [13] defect density, [7,13] mobility, [14,15] and doping density. [14][15][16] Despite this, solar cells based on Cu stoichiometric CuInSe 2 (CIS) have never reached efficiencies above 13.5%, [7,[17][18][19] while Cudeficient CIS yielded efficiencies only up to 15.0%. [20] CIS cells with high CGI are mainly limited by a low open circuit voltage (V OC ), and to a lesser extent, by a reduced fill factor (FF) and current density. However, the implementation of a Cudeficient surface layer has shown to recover the V OC loss in those high CGI cells, while a decrease in current density remains attributed to tun neling recombination. [17,21] Similar improvements of the absorber surface have been achieved with alkali treatments after etching of the secondary phases in Curich samples, [22,23] although most recent results indicate that this treatment may passivates defects that were at least partly generated by the etching in the first place. [24] This suggests that the front absorber surface limits the efficiency of Cu stoichiometric devices. Therefore, it is important to reduce the front interface recombination, besides any other, in such devices.In an earlier publication, we have shown that ungraded CIS solar cells are constrained by recombination at the back interface, [25] which limits the solar cell efficiency. This back sur face recombination can be effectively suppressed by the imple mentation of a single bandgap grading achieved by adding Ga close to the Mo back contact, leading to improved efficiencies up to 16.1% with a bandgap of 1.0 eV absorber [25] and later to 18.0% with application of a RbF postdeposition treatment (PDT). [26] Those solar cells were processed with Cudeficient absorbers (CGI: 0.85-0.90). CIS solar cells processed with high Cu content show lower V OC , and therefore lower efficiency. Believing in recombination as the root cause, we hypothesize that the application of heavy alkali PDT, for example with RbF, may suppress the recombination observed for absorbers with stoichiometric Cu concentrations. To investigate this, we processed and analyzed CISbased solar cells with various Cu concentrations and amounts of RbF during PDT treatment.Here we report a large improvement in efficiency of solar cells processed with Cu composition close to stoichiometry. In State-of-the-art Cu(In,Ga)Se 2 (CIGS) solar cells are grown with considerably substoichiometric Cu concentrations. The resulting defects, as well as potential improvements through increasing the Cu concentration, have been known in the field for many years. However, so far, cells with high Cu concentrations show decreased photovoltaic parameters. In this work, it is shown that RbF postdeposition treatment of CuInSe 2 sola...

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Investigation of high-quality CuInSe2 films with various Cu/In ratios

Cited by 11 publications

References 9 publications

A study on composition, structure and optical properties of copper-poor CIGS thin film deposited by sequential sputtering of CuGa/In and In/(CuGa+In) precursors

A study on composition, structure and optical properties of copper-poor CIGS thin film deposited by sequential sputtering of CuGa/In and In/(CuGa+In) precursors

Doping mechanism in pure CuInSe2

Efficiency Improvement of Near‐Stoichiometric CuInSe₂ Solar Cells for Application in Tandem Devices

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Investigation of high-quality CuInSe2 films with various Cu/In ratios

Cited by 11 publications

References 9 publications

A study on composition, structure and optical properties of copper-poor CIGS thin film deposited by sequential sputtering of CuGa/In and In/(CuGa+In) precursors

A study on composition, structure and optical properties of copper-poor CIGS thin film deposited by sequential sputtering of CuGa/In and In/(CuGa+In) precursors

Doping mechanism in pure CuInSe2

Efficiency Improvement of Near‐Stoichiometric CuInSe2 Solar Cells for Application in Tandem Devices

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Efficiency Improvement of Near‐Stoichiometric CuInSe₂ Solar Cells for Application in Tandem Devices