Electro-optical characterization of photovoltaic devices

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Any: 2015, Tutors: Sergi Hernández Márquez i Julià López VidrierIn this work, we adapted and improved a commercial system designed to measure the external quantum effiency (EQE) and the internal quantum efficiency (IQE) of commercial solar cells. With this purpose, we controlled and synchronized a monochromator and a semiconductor device analyser Agilent B1500A in order to perform different electro-optical measurements being able to measure very low current signals (~10-13 A). To verify that the system was working correctly, we used a Si solar cell whose ll factor, e ciency and spectral response are tabulated. Furthermore, we used this experimental setup to study a Si-NCs/SiO2 superlattice system deposited on a p-type silicon substrate. In this study, we characterized the I(V ) curve of the devices in dark and under white light illumination. We measured the spectral response and IQE of devices containing different NC sizes. IQE of ~14.2 - 20.5 were achieved in the 850-1000 nm wavelength range, and a shift of the IQE edge to higher energies was observed when decreasing the NC size, demostrating electro-optical quantum confinement

Abellaite, NaPb2(CO3)2(OH), a new supergene mineral from the Eureka mine, Lleida province, Catalonia, Spain

The new mineral abellaite (IMA 2014-111), ideally NaPb2 (CO3)2 (OH), is a supergene mineral that was found in one of the galleries of the long-disused Eureka mine, in the southern Pyrenees (Lleida province), Catalonia, Spain. Abellaite is found as sparse coatings on the surface of the primary mineralization, it forms subhedral crystals not larger than 10μm as well as larger pseudohexagonal platelets up to ~ 30μm. Individual crystals commonly have a tabular to lamellar habit and form fairly disordered aggregates. The mineral is associated with a large number of primary minerals (roscoelite, pyrite, uraninite, coffinite, 'carbon', galena, sphalerite, nickeloan cobaltite, covellite, tennantite and chalcopyrite) and supergene minerals (hydrozincite, aragonite, gordaite, As-rich vanadinite andersonite, čejkaite, malachite and devilline). Abellaite is colourless to white, with a vitreous to nacreous lustre. The mineral is translucent, has a white streak and is non-fluorescent. The aggregates of microcrystals are highly friable. The calculated density using the ideal formula is 5.93 g/cm3. The chemical composition of the mineral (the mean of 10 electron microprobe analyses) is Na 3.88, Ca 0.29, Pb 72.03, C 4.17, O 19.47 and H 0.17, total 100.00 wt% (H, C and O by stoichiometry assuming the ideal formula). On the basis of 7 O atoms, the empirical formula of abellaite is Na0.96 Ca0.04 Pb1.98 (CO3)2 (OH). The simplified formula of the mineral is NaPb2 (CO3)2 (OH). The mineral is hexagonal, space group P 63 mc, a = 5.254(2), c = 13.450(5) Å, V = 321.5(2) Å3 and Z = 2. The strongest powder-diffraction lines [d in Å (I) (h k l)] are: 3.193 (100) (0 1 3), 2.627 (84) (1 1 0), 2.275 (29) (0 2 0), 2.242 (65) (0 2 1, 0 0 6), 2.029(95) (0 2 3). Abellaite has a known synthetic analogue, and the crystal structure of the mineral was refined by using crystallographic data of the synthetic phase. The mineral is named in honour of the mineralogist and gemmologist Joan Abella i Creus (b. 1968), who has long studied the deposits of the Eureka mine and who collected the mineral

Structural and optical properties of Al-Tb/SiO2 multilayers fabricated by electron beam evaporation

Light emitting Al-Tb/SiO2 nanomultilayers (NMLs) for optoelectronic applications have been produced and characterized. The active layers were deposited by electron beam evaporation onto crystalline silicon substrates, by alternatively evaporating nanometric layers of Al, Tb, and SiO2. After deposition, all samples were submitted to an annealing treatment for 1 h in N2 atmosphere at different temperatures, ranging from 700 to 1100 °C. Transmission electron microscopy confirmed the NML structure quality, and by complementing the measurements with electron energy-loss spectroscopy, the chemical composition of the multilayers was determined at the nanoscopic level. The average composition was also measured by X-ray photoelectron spectroscopy (XPS), revealing that samples containing Al are highly oxidized. Photoluminescence experiments exhibit narrow emission lines ascribed to Tb3+ ions in all samples (both as-deposited and annealed ones), together with a broadband related to SiO2 defects. The Tb-related emission intensity in the sample annealed at 1100 °C is more than one order of magnitude higher than identical samples without Al. These effects have been ascribed to the higher matrix quality, less SiO2 defects emitting, and a better Tb3+ configuration in the SiO2 matrix thanks to the higher oxygen content favored by the incorporation of Al atoms, as revealed by XPS experiments

Trencant la velocitat del so!

Unitat didàctica de segon d'ESO (especialitat Ciències Naturals). El·laborada dins el Màster de Formació del Professorat d'Educació Secundària i Batxillerat UPF-UOCTutora: Maria del Mar Carrió LlachMentora: Fina Roca PujolEl 2012 Fèlix Baumgarten va batre el rècord mundial de velocitat sense ajuda de cap motor saltant en paracaigudes des de l’estratosfera (38.969 m d’altura). En la caiguda lliure, va trencar la velocitat del so (1.224 km/h) assolint una velocitat màxima de 1.357 km/h. Els alumnes seran investigadors que indagaran perquè en Baumgarten va haver de saltar de tanta altura per superar la velocitat del so i indagaran sobre si l’energia es va conservar durant tot el salt o si part d’aquesta va desaparèixer. En la segona part, ens arriba una sol·licitud des de Port Aventura: volen imitar el salt den Felix Baumgarten i construir la muntanya russa més ràpida del món! Per fer-ho, ens demanen que l’alumnat actuïn com a investigadors per tal de dissenyar-la. Hauran de reflexionar entorn l’altura inicial que haurà de tenir aquesta i a la relació que hi ha amb les diferents altures dels diferents pics d’aquesta. Seguidament, construiran la muntanya russa que han dissenyat i indagaran sobre els efectes del fregament vs. la conservació de l’energia

Abellaite, NaPb2(CO3)2(OH), a new supergene mineral from the Eureka mine, Lleida province, Catalonia, Spain

The new mineral abellaite (IMA 2014-111), ideally NaPb2(CO3)2(OH), is a supergene mineral that was found in one of the galleries of the long-disused Eureka mine, in the southern Pyrenees (Lleida province), Catalonia, Spain. Abellaite is found as sparse coatings on the surface of the primary mineralization, it forms subhedral crystals not larger than 10 mm as well as larger pseudohexagonal platelets up to ∼30 μm. Individual crystals commonly have a tabular to lamellar habit and form fairly disordered aggregates. The mineral is associated with a large number of primary minerals (roscoelite, pyrite, uraninite, coffinite, 'carbon', galena, sphalerite, nickeloan cobaltite, covellite, tennantite and chalcopyrite) and supergene minerals (hydrozincite, aragonite, gordaite, As-rich vanadinite andersonite, čejkaite, malachite and devilline). Abellaite is colourless to white, with a vitreous to nacreous lustre. The mineral is translucent, has a white streak and is non-fluorescent. The aggregates of microcrystals are highly friable. The calculated density using the ideal formula is 5.93 g/cm3. The chemical composition of the mineral (the mean of 10 electron microprobe analyses) is - Na 3.88, Ca 0.29, Pb 72.03, C 4.17, O 19.47 and H 0.17, total 100.00 wt% (H, C and O by stoichiometry assuming the ideal formula). On the basis of 7 O atoms, the empirical formula of abellaite is Na0.96Ca0.04Pb1.98(CO3)2(OH). The simplified formula of the mineral is NaPb2(CO3)2(OH). The mineral is hexagonal, space group P63mc, a = 5.254(2), c = 13.450(5) Å, V= 321.5(2)Å3 and Z = 2. The strongest powder-diffraction lines [d in Å (I) (h k l)] are: 3.193 (100) (0 1 3), 2.627 (84) (1 1 0), 2.275 (29) (0 2 0), 2.242 (65) (0 2 1, 0 0 6), 2.029(95) (0 2 3). Abellaite has a known synthetic analogue, and the crystal structure of the mineral was refined by using crystallographic data of the synthetic phase. The mineral is named in honour of the mineralogist and gemmologist Joan Abella i Creus (b. 1968), who has long studied the deposits of the Eureka mine and who collected the mineral. © 2017 E. Schweizerbart'sche Verlagsbuchhandlung.The work is partially funded by ERDF-EU Ref. CSIC10-4E-141.Peer reviewe

Abellaite, NaPb2(CO3)2(OH), a new supergene mineral from the Eureka mine, Lleida province, Catalonia, Spain

The new mineral abellaite (IMA 2014-111), ideally NaPb2 (CO3)2 (OH), is a supergene mineral that was found in one of the galleries of the long-disused Eureka mine, in the southern Pyrenees (Lleida province), Catalonia, Spain. Abellaite is found as sparse coatings on the surface of the primary mineralization, it forms subhedral crystals not larger than 10μm as well as larger pseudohexagonal platelets up to ~ 30μm. Individual crystals commonly have a tabular to lamellar habit and form fairly disordered aggregates. The mineral is associated with a large number of primary minerals (roscoelite, pyrite, uraninite, coffinite, 'carbon', galena, sphalerite, nickeloan cobaltite, covellite, tennantite and chalcopyrite) and supergene minerals (hydrozincite, aragonite, gordaite, As-rich vanadinite andersonite, čejkaite, malachite and devilline). Abellaite is colourless to white, with a vitreous to nacreous lustre. The mineral is translucent, has a white streak and is non-fluorescent. The aggregates of microcrystals are highly friable. The calculated density using the ideal formula is 5.93 g/cm3. The chemical composition of the mineral (the mean of 10 electron microprobe analyses) is Na 3.88, Ca 0.29, Pb 72.03, C 4.17, O 19.47 and H 0.17, total 100.00 wt% (H, C and O by stoichiometry assuming the ideal formula). On the basis of 7 O atoms, the empirical formula of abellaite is Na0.96 Ca0.04 Pb1.98 (CO3)2 (OH). The simplified formula of the mineral is NaPb2 (CO3)2 (OH). The mineral is hexagonal, space group P 63 mc, a = 5.254(2), c = 13.450(5) Å, V = 321.5(2) Å3 and Z = 2. The strongest powder-diffraction lines [d in Å (I) (h k l)] are: 3.193 (100) (0 1 3), 2.627 (84) (1 1 0), 2.275 (29) (0 2 0), 2.242 (65) (0 2 1, 0 0 6), 2.029(95) (0 2 3). Abellaite has a known synthetic analogue, and the crystal structure of the mineral was refined by using crystallographic data of the synthetic phase. The mineral is named in honour of the mineralogist and gemmologist Joan Abella i Creus (b. 1968), who has long studied the deposits of the Eureka mine and who collected the mineral

Structural and optical properties of Al-Tb/SiO2 multilayers fabricated by electron beam evaporation

Light emitting Al-Tb/SiO2 nanomultilayers (NMLs) for optoelectronic applications have been produced and characterized. The active layers were deposited by electron beam evaporation onto crystalline silicon substrates, by alternatively evaporating nanometric layers of Al, Tb, and SiO2. After deposition, all samples were submitted to an annealing treatment for 1 h in N2 atmosphere at different temperatures, ranging from 700 to 1100 °C. Transmission electron microscopy confirmed the NML structure quality, and by complementing the measurements with electron energy-loss spectroscopy, the chemical composition of the multilayers was determined at the nanoscopic level. The average composition was also measured by X-ray photoelectron spectroscopy (XPS), revealing that samples containing Al are highly oxidized. Photoluminescence experiments exhibit narrow emission lines ascribed to Tb3+ ions in all samples (both as-deposited and annealed ones), together with a broadband related to SiO2 defects. The Tb-related emission intensity in the sample annealed at 1100 °C is more than one order of magnitude higher than identical samples without Al. These effects have been ascribed to the higher matrix quality, less SiO2 defects emitting, and a better Tb3+ configuration in the SiO2 matrix thanks to the higher oxygen content favored by the incorporation of Al atoms, as revealed by XPS experiments