It is shown that de-confinement can be achieved in high multiplicity non jet p̄p collisions at √s = 1.8 TeV Fermi National Accelerator Laboratory(FNAL- E735) experiment. In this paper we have ...analyzed the transverse momentum spectrum in the framework of the clustering of color sources. This frame-work naturally predicts the reduction in the charged particle multiplicity with respect to the value expected from the number of independent strings. Results are presented for both thermodynamic and transport properties. The initial temperature and energy density are obtained from the data via the color reduction factor F(ξ) and the associated string density parameter ξ. The results for he trace anomaly Δ and shear viscosity to entropy density ratio(η/s) are presented. These results confirm our earlier observation that the de-confined state of matter was created in high multiplicity events in p̄p collisions at √s = 1.8 TeV.
We have produced CZTSSe solar cells by a sequential growth process. First, CZTS precursors were deposited on Mo-coated soda lime glass substrates by chemical spray pyrolysis from an aqueous solution ...containing Cu, Zn and Sn metal salts and thiourea. In a second step the precursor was selenized at 530 °C for 8 min, resulting in fair solar cell properties. Further, we have investigated the influence of a 20 nm CuGe seed layer, which was sputtered on the Mo-surface prior to CZTS precursor deposition, on the morphology of the resulting absorber and on the performance of CZTSSe solar cells. We observe that the formation of MoSe
2
and the consequent decomposition reactions at the back contact region of the CZTSSe layers during the annealing process were suppressed by introducing the CuGe seed layer, and that grain growth at the Mo/CZTSSe interface region was enhanced. The performance of CZTSSe solar cells prepared with a 20 nm CuGe seed layer shows considerable improvement compared to the processing without CuGe introduction.
A CuGe seed layer suppresses the formation of MoSe
2
and the consequent decomposition reaction at the Mo/CZTSSe interface during selenization.
This paper provides an overview of the physical vapor technologies used to synthesize Cu2ZnSn(S,Se)4 thin films as absorber layers for photovoltaic applications. Through the years, CZT(S,Se) thin ...films have been fabricated using sequential stacking or co-sputtering of precursors as well as using sequential or co-evaporation of elemental sources, leading to high-efficient solar cells. In addition, pulsed laser deposition of composite targets and monograin growth by the molten salt method were developed as alternative methods for kesterite layers deposition. This review presents the growing increase of the kesterite-based solar cell efficiencies achieved over the recent years. A historical description of the main issues limiting this efficiency and of the experimental pathways designed to prevent or limit these issues is provided and discussed as well. A final section is dedicated to the description of promising process steps aiming at further improvements of solar cell efficiency, such as alkali doping and bandgap grading.
Results of defect levels spectroscopy on epitaxial and polycrystalline CuInSe2 by photocurrent and capacitance methods are presented. Electronic parameters of defect levels found by photocurrent ...methods are compared with those obtained through the use of capacitance spectroscopy on CuInSe2 solar cells. In the discussion, we include the Meyer–Neldel plot as a method of differentiation between the levels in the case of parameter variation between samples and depending on measurement conditions. The levels common for all compounds from the Cu(In,Ga)Se2 family are specified. The origin of the N1 and N2 defect levels frequently observed in the capacitance spectra of solar cells is discussed and the coincidence of the N2 level and the E4 bulk level is shown.
► Parameters of seven defect levels in CuInSe2 are collected. ► Some that are observed in CuGaSe2 defects are confirmed in CuInSe2. ► Candidate for recombination center is observed in CuInSe2 and CuGaSe2. ► First database of defect levels in CuInSe2 is created.
Optoelectronic properties of Cu(In
1–
x
Ga
x
)Se
2 (CIGSe) have been studied by confocal microscopic photoluminescence (PL) with lateral submicron resolution. The lateral patterns of PL-yields, ...varying by factors of up to 10 between regimes with low and high emission, exhibit structures in the length scale of some micrometers (3–10 μm) whereas geometrical sizes of individual grains are in the 1-μm range or below. In addition to the local PL-variation, we observe that the geometrical extension of PL-patterns depend on excitation flux, that spectral PL-shapes are varying with respect to different onset energies of the low-energy wings, signalizing different local band gaps, and that low-energy PL-wings get steeper with rise in excitation flux pointing towards potential fluctuations and their respective screening by photoexcited excess carriers.
We have examined charged multiplicities arising from
p−
p and
p−
p
̄
collisions over the range of center of mass energies,
s
, from 30 GeV to 1800 GeV. Results from Tevatron experiment E735 support ...the presence of double parton interactions. These processes can be seen to account for a large fraction of the increase in the non single diffraction inelastic cross section from energies of about 200 GeV to 1800 GeV.
We analyze the quality of the photoexcited state in Cu(In,Ga)Se
2 absorbers prepared under conditions similar to module pilot line production with different Ga-admixtures in terms of the splitting of ...the quasi-Fermi levels by confocal microscopic photoluminescence (PL) with submicron lateral resolution. The lateral luminescence patterns exhibit structures in the length scale of some micrometers (3–10 μm) which by far exceed the geometrical sizes of individual grains with diameters of 1 μm or below, detected simultaneously by optical reflection, and by scans of atomic force microscopy (AFM). The luminescence yields recorded at (83–250) K and at about (10
4–10
2) air mass 1.5 (AM1.5)-equivalent photon fluxes show lateral alterations by factors (2–20) depending on Ga-content, excitation level, and temperature. From temperature and excitation regimes, we are able to extrapolate the lateral variations towards 300 K and AM1.5-equivalent fluxes, and we translate PL-yields into lateral alterations of the splitting of quasi-Fermi-levels Δ(
E
Fn−
E
Fp) and of corresponding variations in maximum hypothetic open circuit voltages
V
oc.
PDF
