XIS: A Low-current, High-voltage Back-junction Back-contact Device

AbstractIn this paper we present experimental results of a low-current, high-voltage back-junction back-contact device. The concept is demonstrated by the successful transformation of finished IBC cells into XIS (Crystalline Silicon Interconnected Strips) devices, leading to 8.5V for a series connection of 14 strip cells. Different grooving methods for cell separation were evaluated regarding the effect on the quality of the groove surface. The effect of the groove passivation, which is regarded as a critical parameter to obtain high-efficiency XIS devices, was simulated to gain a better understanding of the processing requirements

Spatially resolved generation profiles for building, land and water-bound PV: a case study of four Dutch energy transition scenarios

Alongside a transition from steerable and centralized traditional electricity generation to intermittent and more decentralized renewable electricity generation from solar panels and wind turbines, Dutch energy transition scenarios project a widespread deployment of heat pumps and electric vehicles towards 2050. While clearly contributing to the decarbonization of the Dutch energy system, these developments impose challenges regarding electricity supply-demand mismatch and grid congestion. Spatially resolved electricity demand and supply profiles are required to gain a better insight into where and when such problems are likely to occur within the different scenarios. The present paper focuses on Dutch solar energy supply and features the construction of geodatabases of scenario-specific, spatially resolved electricity generation profiles for building, land and water-bound PV. Country-level PV capacities are geographically distributed based on spatial variance in roof PV potential and availability of suitable land and water use areas. Corresponding electricity generation profiles are constructed using historical meteorological measurements, a diffuse fraction model and a anisotropic transposition model. Empirically found performance ratio profiles are applied to account for a multitude of performance loss factors, including shading, dust and inverter efficiency. In 2050, building-bound capacity is projected to show only limited overlap with both land-bound and water-bound PV capacity. On the other hand, regions with considerable water-bound PV capacity also tend to show considerable land-bound PV capacity. Compared to the present-day situation, yearly country-level PV electricity generation is projected to be a factor 18.5, 15.7, or 7.7 higher in 2050 when respectively following the Regional, National or International Steering scenarios

Step edge selection during ion erosion of Cu(001)

Upon Ar+ ion erosion of a Cu(001) surface, we observed with HR-LEED faceted structures on the surface oriented preferentially along ¿100¿ at 200 K and along ¿110¿ at 330 K. These results are evaluated with a geometric rule, relating under kinetic conditions the orientation of the surviving steps to their advance rates. Application of this generic rule demonstrates that the ¿100¿ steps advance slowest. This reveals enhanced interlayer mass transport across these steps. We also show that a transition from kinetically favored step orientation into the thermodynamically favored one occurs at very short time scales even near room temperature

Seeded-Growth Approach to Selective Metallization of Microcontact-Printed Patterns

We report on a versatile nanocolloidal route to obtain large-scale conducting metal microstructures on a silicon oxide substrate. By using microcontact printing of an aminosilane, we create functionalized regions on the silicon oxide surface onto which gold nanoparticles selectively adhere. By using an established electroless, seeded-growth process, the individual, isolated gold nanocrystals are enlarged past the percolation threshold to form conducting metal structures. Quantitative characterization of metal coverage, thickness, and roughness has been performed with scanning electron microscopy and spectroscopic ellipsometry

Von dreidimensionalen Kraterstrukturen zu hochperiodischen, eindimensionalen Streifenstrukturen

Am Beispiel einer Cu(001)-Oberfläche wird gezeigt, daß der Beschuß von Metalloberflächen mit 800eV Ar-Ionen dazu genutzt werden kann, um in Hinsicht auf Symmetrie und Periodizität verschiedenartige Defektstrukturen zu erzeugen. Bei senkrechtem Einfall des Ionenstrahls ergeben sich 3D-Kraterstrukturen mit ausgeprägter Vierfachsymmetrie. Dabei bestimmt die Probentemperatur während des Ionenbeschusses, ob Stufenkanten der Defektstrukturen präferentiell entlang dichtgepackter {110}-Richtungen oder entlang offenerer {100}-Richtungen verlaufen. Ein Abweichen vom senkrechten Einfall hin bis zu einem streifenden Einfall des Ionenstrahls führt zu einem Bruch der Vierfachsymmetrie mit einer resultierenden Zweifachsymmetrie der geätzten Defektstrukturen. Für einen streifenden Einfall des Ionenstrahls von 80 Grad ergeben sich hochperiodische, eindimensionale Linienstrukturen, die nur ein bis zwei Atomlagen tief sind. Die Vorzugsrichtung der Defektstrukturen bei streifenden Einfall wird alleine durch den einfallenden Ionenstrahl und nicht mehr, wie bei senkrechtem Einfall, durch die Probentemperatur bestimmt

Ellipsometric characterisation of heterogeneous 2D layers

Heterogeneous two-dimensional layers have been the subjects of many ellipsometric studies. An unambiguous characterization of especially metal heterogeneous layers is not straightforward. Adsorption of Au nanocolloids leads to a well-defined heterogeneous layer, although the analysis of ellipsometric spectra is not simple. Standard effective medium theories are shown not to be capable of a correct description. The thin island film theory developed by Bedeaux and Vlieger (Optical properties of surface Imperial College Press (2002)), which evaluates a spherical Au colloid as an excess polarizability at the surface, provides a good framework for the analysis. Both the image dipole and the lateral distribution can be incorporated in a straightforward manner. The influence of the change in particle shape from spherical to prolate is evaluated and shows that already a small change in shape leads to large influences in the optical response. This strong effect is due to the influence of shape on the depolarization factors and especially due to the large optical contrast between the Au colloids and the ambient. In contrast to this, the adsorption of the strongly aspherical protein fibrinogen can be analyzed straightforwardly. Only the adsorbed amount of protein on the surface is recorded in-situ. This is the result of the minimal refractive index contrast between proteins and water, which results in a negligible influence of shape on the optical response