Electron energy-loss spectroscopy of boron-doped layers in amorphous thin film silicon solar cells

Electron energy-loss spectroscopy (EELS) is used to study p-doped layers in n-i-p amorphous thin film Si solar cells grown on steel foil substrates. For a solar cell in which an intrinsic amorphous hydrogenated Si (a-Si-H) layer is sandwiched between 10-nm-thick n-doped and p-doped a-Si:H layers, we assess whether core-loss EELS can be used to quantify the B concentration. We compare the shape of the measured B K edge with real space ab initio multiple scattering calculations and show that it is possible to separate the weak B K edge peak from the much stronger Si L edge fine structure by using log-normal fitting functions. The measured B concentration is compared with values obtained from secondary ion mass spectrometry, as well as with EELS results obtained from test samples that contain ∼200-nm-thick a-Si:H layers co-doped with B and C. We also assess whether changes in volume plasmon energy can be related to the B concentration and/or to the density of the material and whether variations of the volume plasmon line-width can be correlated with differences in the scattering of valence electrons in differently doped a-Si:H layers.Fil: Duchamp, M.. Helmholtz Gemeinschaft. Forschungszentrum Jülich; AlemaniaFil: Boothroyd, C.B.. Helmholtz Gemeinschaft. Forschungszentrum Jülich; AlemaniaFil: Moreno, Mario Sergio Jesus. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Van Aken, B.B.. No especifíca;Fil: Soppe, W.J.. No especifíca;Fil: Dunin-Borkowski, R.E.. Helmholtz Gemeinschaft. Forschungszentrum Jülich; Alemani

Electron energy-loss spectroscopy of boron-doped layers in amorphous thin film silicon solar cells

Electron energy-loss spectroscopy (EELS) is used to study p-doped layers in n-i-p amorphous thin film Si solar cells grown on steel foil substrates. For a solar cell in which an intrinsic amorphous hydrogenated Si (a-Si-H) layer is sandwiched between 10-nm-thick n-doped and p-doped a-Si:H layers, we assess whether core-loss EELS can be used to quantify the B concentration. We compare the shape of the measured B K edge with real space ab initio multiple scattering calculations and show that it is possible to separate the weak B K edge peak from the much stronger Si L edge fine structure by using log-normal fitting functions. The measured B concentration is compared with values obtained from secondary ion mass spectrometry, as well as with EELS results obtained from test samples that contain ∼200-nm-thick a-Si:H layers co-doped with B and C. We also assess whether changes in volume plasmon energy can be related to the B concentration and/or to the density of the material and whether variations of the volume plasmon line-width can be correlated with differences in the scattering of valence electrons in differently doped a-Si:H layers.Fil: Duchamp, M.. Helmholtz Gemeinschaft. Forschungszentrum Jülich; AlemaniaFil: Boothroyd, C.B.. Helmholtz Gemeinschaft. Forschungszentrum Jülich; AlemaniaFil: Moreno, Mario Sergio Jesus. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Van Aken, B.B.. No especifíca;Fil: Soppe, W.J.. No especifíca;Fil: Dunin-Borkowski, R.E.. Helmholtz Gemeinschaft. Forschungszentrum Jülich; Alemani

Место и роль ценностей в механизме социализации

В статье рассматривается специфика механизма социализации и проблема ценностных ориентаций в условиях социокультурных трансформаций украинского общества. Определяются ценностные ориентиры гражданского общества как приоритетного для Украины.У статті розглядається специфика механізму соціалізації і проблема цінностних орієнтацій в умовах соціокультурних трансформацій українського суспільства. Визначаються цінностні орієнтири громадянського суспільства як приоритетного для України.The article deals with peculiarities of socialization and the problem of value ori-entation under the conditions of socio-cultural transformations of the Ukrainian society. We also define value orientation of the civil society as optimal for Ukraine

Polydisperse Adsorption: Pattern Formation Kinetics, Fractal Properties, and Transition to Order

We investigate the process of random sequential adsorption of polydisperse particles whose size distribution exhibits a power-law dependence in the small size limit, $P(R)\sim R^{\alpha-1}$. We reveal a relation between pattern formation kinetics and structural properties of arising patterns. We propose a mean-field theory which provides a fair description for sufficiently small $\alpha$. When $\alpha \to \infty$, highly ordered structures locally identical to the Apollonian packing are formed. We introduce a quantitative criterion of the regularity of the pattern formation process. When $\alpha \gg 1$, a sharp transition from irregular to regular pattern formation regime is found to occur near the jamming coverage of standard random sequential adsorption with monodisperse size distribution.Comment: 8 pages, LaTeX, 5 figures, to appear in Phys.Rev.

Student and tutor perceptions on attributes of effective problems in problem-based learning

This study aimed to identify the attributes that students and tutors associated with effective PBL problems, and assess the extent to which these attributes related to the actual effectiveness of problems. To this end, students and tutors in focus groups were asked to discuss about possible attributes of effective problems. The same participants were then asked to individually and independently judge eight sample problems they had worked with. Text analysis of the focus group discussion transcripts identified eleven problem attributes. Participants' judgments of the sample problems were then frequency-scored on the eleven problem attributes. Relating the participants' judgments with the entire student cohort's grades yielded high and significant correlations, suggesting that the eleven problem attributes reflect aspects of problem effectiveness