Optical properties of epitaxial CuGaS2 layers on Si(111)

Eberhardt, J.; Metzner, H.; Hahn, Trudi Bellardo; Reislöhner, U.; Cieslak, J.; Großner, Ulrike; Goldhahn, R.; Hudert, Florian; Gobsch, G.; Witthuhn, W.

doi:10.1016/s0022-3697(03)00199-9

Cited by 24 publications

(13 citation statements)

References 10 publications

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“…The above named excitonic peaks do not show appreciable temperature dependence below 70 K. However intensity of the bound exciton decreases as temperature increases from 10 to 70 K. The high temperature luminescence spectra (> 70 K) presented by free exctiton, which is broadened and thermally dissolved up to room temperature. The observed near-band gap PL is in a good agreement with the PL properties of epitaxial CuGaS 2 layers on Si (1 1 1) [8,12], GaAs and GaP [6] but in contrast to the bulk CuGaS 2 where bound exciton peak is dominated at high temperature PL spectra [6]. The latter behavior of the reported PL on bulk CuGaS 2 is probably due to some imperfections of the crystal and/or presence of defects in the studied samples.…”

Section: Resultssupporting

confidence: 84%

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Temperature dependence of the exciton gap in monocrystalline CuGaSe₂

Meeder¹,

Jäger-Waldau²,

Arushanov

et al. 2003

J. Phys.: Condens. Matter

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Single crystals of CuGaS 2 have been grown by chemical vapour transport. Their near-band gap photoluminescence properties were investigated in the temperature range of 10-300 K. The variation of the exciton gap energy with temperature was studied by means of a three-parameter thermodynamic model, the Einstein model and the Pássler model. Valúes of the band gap at T=0 K, of a dimensionless constant related to the electron-phonon coupling, and of an effective and a cutoff phonon energy have been estimated. It has also been found that the major contribution of phonons to the shift of £ g as a Keywords: function of T in CuGaS 2 is mainly from optical phonons. Chalcopyrite Photoluminescence Spectroscopy 2.42 2.44 2.46 2.48 2.50 2.52 2.54 2.56 Energy (eV)

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Section: Resultssupporting

confidence: 84%

“…So far, the characteristics of CuGaS 2 single crystals have not been yet well studied. Some optical measurements (absorption, reflectivity spectra, pholuminescence and photoreflectance, Raman scattering and spectroscopic ellipsometry) were carried out on CuGaS 2 thin films and bulk samples [3][4][5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of the exciton gap in monocrystalline CuGaSe₂

Meeder¹,

Jäger-Waldau²,

Arushanov

et al. 2003

J. Phys.: Condens. Matter

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“…The strong broadening of the PL peak is due to the strong increase of the exciton (electron)-phonon interaction at room temperature. 28 Similar experimental tendencies have been observed in temperature dependence of photoluminescence measurements of CuGaS 2 crystals 29,30 and CuGaS 2 films epitaxially grown on Si(111) substrates. 28 The Raman spectrum is dominated by a very strong line at 311 cm À1 exhibiting A 1 symmetry (see Fig.…”

Section: Structural and Optical Propertiessupporting

confidence: 70%

Conducting behavior of chalcopyrite-type CuGaS₂ crystals under visible light

Cholula-Díaz

Barzola‐Quiquia

Kranert

et al. 2014

Phys. Chem. Chem. Phys.

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Millimeter size high quality crystals of CuGaS2 were grown by chemical vapor transport. The highly ordered chalcopyrite structure is confirmed by X-ray diffraction and Raman spectroscopy. According to energy dispersive X-ray spectroscopy the composition of the crystals is very close to the formula CuGaS2. Room temperature photoluminescence measurements indicate the presence of an emission peak at about 2.36 eV that can be related to a donor-acceptor pair transition. The electrical resistance as a function of temperature is very well described by the Mott variable range hopping mechanism. Room temperature complex impedance spectroscopy measurements were performed in the alternating current frequency range from 40 to 10(7) Hz in the dark and under normal light. According to the impedance spectroscopy data the experimental results can be well described by two circuits in series, corresponding to bulk and grain boundary contributions. An unusual positive photoresistance effect is observed in the frequency range between 3 and 30 kHz, which we suggest to be due to intrinsic defects present in the CuGaS2 crystal.

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“…24,25 When only sulfur was used during the annealing, the highest E G value of 2.38 eV was obtained, which is consistent with reported values for CuGaS 2 . 26,27 Because sulfur-containing chalcopyrites always have higher band gaps than their selenium-containing counterparts [e.g., CuInSe 2 (1.0 eV) versus CuInS 2 (1.5 eV)], 9,28 the increase in E G as the ratio of sulfur-to-selenium (S/Se) mass ratio used during annealing increases suggests that the sulfoselenization process has successfully replaced part or all selenium in CuGaSe 2 with sulfur to form CuGa(S,Se) 2 .…”

Section: Resultsmentioning

confidence: 99%

Wide Band Gap CuGa(S,Se)₂ Thin Films on Transparent Conductive Fluorinated Tin Oxide Substrates as Photocathode Candidates for Tandem Water Splitting Devices

2018

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The purpose of this work was to explore the potential of CuGa(S,Se) 2 thin films as wide-E G top cell absorbers for photoelectrochemical (PEC) water splitting. A synthesis was developed on fluorinated tin oxide (FTO) photocathodes by converting copper-rich co-evaporated CuGaSe 2 into CuGa(S,Se) 2 via a post-deposition annealing. We found it necessary to first anneal CuGaSe 2 at lowtemperature in sulfur then at high-temperature in nitrogen to preserve the transparency and conductivity of the FTO. Using this two-step synthesis, we fabricated a 1.72 eV CuGa(S,Se) 2 photocathode with a saturation current density and photocurrent onset potential of 10 mA/cm 2 and −0.20 V versus reversible hydrogen electrode, respectively. However we found that the PEC performance and sub-E G transmittance, worsened with increasing copper content. Using flatband potential measurements and the Gerischer model, we show that divergences in PEC performance of CuGa(S,Se) 2 photocathodes can be explained by differences in conduction band minimums and Fermi levels. We also explain that sub-E G transmittance is likely hampered by a defect band 100−400 meV below E C . Additional external quantum efficiency measurements of a high-efficiency 1.1 eV Cu(In,Ga)Se 2 photovoltaic driver, while shaded by the CuGa(S,Se) 2 photocathode, yielded a short-circuit current density of 4.14 mA/cm 2 revealing that CuGa(S,Se) 2 shows promise as a top cell for PEC water splitting.

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Optical properties of epitaxial CuGaS2 layers on Si(111)

Cited by 24 publications

References 10 publications

Temperature dependence of the exciton gap in monocrystalline CuGaSe₂

Temperature dependence of the exciton gap in monocrystalline CuGaSe₂

Conducting behavior of chalcopyrite-type CuGaS₂ crystals under visible light

Wide Band Gap CuGa(S,Se)₂ Thin Films on Transparent Conductive Fluorinated Tin Oxide Substrates as Photocathode Candidates for Tandem Water Splitting Devices

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Optical properties of epitaxial CuGaS2 layers on Si(111)

Cited by 24 publications

References 10 publications

Temperature dependence of the exciton gap in monocrystalline CuGaSe2

Temperature dependence of the exciton gap in monocrystalline CuGaSe2

Conducting behavior of chalcopyrite-type CuGaS2 crystals under visible light

Wide Band Gap CuGa(S,Se)2 Thin Films on Transparent Conductive Fluorinated Tin Oxide Substrates as Photocathode Candidates for Tandem Water Splitting Devices

Contact Info

Product

Resources

About

Temperature dependence of the exciton gap in monocrystalline CuGaSe₂

Temperature dependence of the exciton gap in monocrystalline CuGaSe₂

Conducting behavior of chalcopyrite-type CuGaS₂ crystals under visible light

Wide Band Gap CuGa(S,Se)₂ Thin Films on Transparent Conductive Fluorinated Tin Oxide Substrates as Photocathode Candidates for Tandem Water Splitting Devices