Material properties of high mobility TCOs and application to solar cells

The benefit of achieving high electron mobilities in transparent conducting oxides TCOs is twofold they first exhibit superior optical properties, especially in the NIR spectral range, and secondly their low resistivity enables the usage of thinner films. Remarkably high mobilities can be obtained in Al doped zinc oxide by post deposition annealing under a protective layer. The procedure has not only shown to increase mobility, but also strongly reduces sub bandgap absorption. Extensive optical, electrical and structural characterization is carried out in the films in order to clarify the microscopic origins of the changes in material properties. While the annealing of defect states, most likely deep acceptors, seems clear, earlier results also suggest some influence of grain boundaries. Tailing, on the contrary, seems to be linked to extended defects. In application to a Si H c Si H thin film solar cells the films have already shown to increase spectral response. When reducing the film thickness, the main challenge is to provide a suitable light trapping scheme. Normally this is achieved by a wet chemical etching step in diluted HCl, which provides a surface structure with suitable light scattering properties. Therefore a TCO independent light scattering approach using textures glass was applied in conjunction with the high mobility zinc oxide. The substrate enables the use of very thin TCO layers with a strongly reduced parasitic absorptio

Естественная радиоактивность кольчугинской серии отложений Ленинского геолого-экономического района Кузбасса

Рассматриваются на основании исследования 1435 образцов горных пород естественные радиоактивные свойства мелко- и крупнозернистого алевролитов и мелкозернистого песчаника, а также каменных углей. Отмечается различие по естественной радиоактивности между основными литологическими разностями пород, слагающих кольчугинскую серию. Естественная радиоактивность пород закономерно уменьшается от алевролитов к песчаникам и к углям. Угли по естественной радиоактивности резко отличаются от вмещающих пород

A Subfield Lattice Attack on Overstretched NTRU Assumptions:Cryptanalysis of Some FHE and Graded Encoding Schemes

International audienc

Comorbid substance abuse and brain morphology in recent-onset psychosis

The aim of the presented study was to compare schizophrenia and schizoaffective patients early in the course of the disease with and without comorbid substance abuse disorder (SUD vs. NSUD) with regard to brain morphology. In a prospective design 41 patients (20 SUD vs. 21 NSUD) diagnosed as recent-onset schizophrenia or schizoaffective disorder consecutively admitted to hospital received standardized psychopathological evaluation (BPRS, SANS, MADRS, CGI, GAF) and MRI scanning with volumetric measurement of superior temporal gyrus (STG), amygdala-hippocampal complex, and cingulum. Patients with SUD (primarily cannabis) were significantly younger, predominantly male and had a lower socioeconomic status. Despite less attentional impairment (SANS subscore) and elevated anxiety/depression (BPRS subscore) in patients with SUD compared to NSUD, no other psychopathological differences could be detected. There were no differences in the assessed temporolimbic brain morphology between the two subgroups. In conclusion, in this study substance abuse in recent-onset psychosis had no effect on brain morphology and the earlier onset of psychosis in patients with comorbid SUD could not be explained by supposed accentuated brain abnormalities in temporolimbic regions

The density of tuples restricted by relatively r-prime conditions

In order to consider j-wise relative r-primality conditions that do not necessarily require all j-tuples of elements in a Dedekind domain to be relatively r-prime, we define the notion of j-wise relative r-primality with respect to a fixed j-uniform hypergraph H. This allows us to provide further generalisations to several results on natural densities not only for a ring of algebraic integers O, but also for the ring F_q[x]

Reactive magnetron sputtering of ZnO Al

Transparent conductive oxides TCOs , such as aluminium doped zinc oxide ZnO Al , play an important role in thin film photovoltaics. As a material for front contacts, ZnO Al is standard in industrial scale production, especially in the field of Cu In,Ga Se2 solar cells. Over the last few years, there has been a strong push to use ZnO Al films on glass as substrates for amorphous or amorphous microcrystalline silicon solar cells, and these films have now been introduced as an alternative to the typically used fluorine doped tin oxide SnO2 F films in production. Sputtering coaters for large area deposition of ZnO Al are widely available, and ZnO Al films are produced in these coaters by sputtering of ceramic targets. This technology offers high process stability and is therefore favoured over reactive sputtering of metallic targets. With respect to cost and quality, however, the reactive process is an interesting alternative. In this paper we will give an overview of the process of reactive sputtering of ZnO Al and discuss the most important insight

Microtribological rating of transparent conducting oxide for thin film solar cells

In this study, the mechanical properties of transparent conducting oxide (TCO) deposited on glass substrates, namely, aluminium doped zinc oxide (ZnO:Al) and fluorine doped tin oxide (SnO2:F) for the application of amorphous or amorphous/microcrystalline silicon solar cells, were investigated. The ZnO : Al thin films were deposited by either inline reactive ac magnetron sputtering or radio frequency magnetron sputtering utilising ceramic targets. The SnO2:F thin films were prepared using either inline or offline chemical vapour deposition (CVD). The micromechanical properties such as elastic and permanent deformation, microtribological properties and scratch resistance were measured to assess the film properties. The micro-structure-analysis method (MISTAN) was used to characterise those properties in situ with high local resolution. The inline reactive ac magnetron sputtered ZnO:Al films show relatively good scratch resistance. The surface structure of ZnO:Al films can be roughened by an etching process in order to enhance the scattered light into the cells. At the same time, the microfriction of the ZnO:Al films under the same load is higher after the etching process. Also the elastic and permanent deformation of inline reactive ac magnetron sputtered ZnO:Al films are increased after etching. The etching process has a significant impact on the radio frequency magnetron with ceramic targets deposited ZnO:Al films, since the scratch resistance of these films can be significantly improved by the etching process. The results show that the SnO2:F films possess poor mechanical resistance and planar surface structure

Deposition of surface passivation layers for silicon heterojunction solar cells by hot-wire CVD

Thin intrinsic amorphous silicon layers acting as surface passivation layers have proven to play an essential role for the performance of silicon heterojunction (SHJ) solar cells. By using hot-wire chemical vapor deposition (HWCVD), intrinsic hydrogenated amorphous silicon layers (a-Si:H) for SHJ solar cells were deposited on both sides of textured n-type semi-square silicon wafers, with sizes of 156 x 156 mm². Amongst the investigated deposition process parameters, substrate temperature and film thickness were identified to have the greatest influence on the passivation properties. Differently prepared passivation layers were characterized by measurements of the minority-carrier lifetimes using the photoconductance method. The best a-Si:H layers were deposited by activating pure silane (SiH4) gas by tungsten wires at pressures around 1.3 Pa and wire temperatures of about 2100 °C. At film thicknesses of approximately 12 nm average minority-carrier lifetimes of 3.5 ms were achieved