Articles you may be interested in X-ray reciprocal space maps and x-ray scattering topographic observation of GaN layer on GaAs (001) in plasma-assisted molecular beam epitaxy Effect of substrate misorientation on xray rocking curves from InGaAs relaxed epitaxial layers

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Crystalline silicon based photovoltaics continues to be the dominant technology for large scale deployment of solar energy. While impressive cost gains in silicon based PV have come with scale, there remains a strong push for increased efficiencies and further lowering of manufacturing costs to achieve true grid parity. So far, however, there has not been a production proven approach that reduces the cost while maintaining or increasing the efficiency. Attempts to reduce the amount of silicon used, for example, have led to development of various kerfless wafer manufacturing approaches. While some of these approaches have shown the potential for reduced costs, they also compromise the efficiency mainly due to the inferior quality of the material.Epitaxy based kerfless silicon wafers, on the other hand, has shown the potential to reverse this trend offering lower manufacturing costs while maintaining or even enhancing the efficiency due to the high quality of the n-type and p-type silicon epitaxial (Epi) wafers. In this work, we present key aspects of Crystal Solar’s patented high throughput production silicon epitaxial reactor and its use in the manufacture of standard thickness N and P wafers. Besides the advantage of having significantly reduced cost, these Epi wafers have high quality, better mechanical strength and resistance to light inducted degradation due to significantly reduced oxygen content.

The growth morphology of ErAs on [001] GaAs with thicknesses ranging from 2 atomic layers to 400 Å is investigated using x-ray specular reflectivity. This epitaxial system displays rich morphological behavior and we observe the evolution from discontinuous to continuous layers at just a few monolayers and qualitative changes occur in layer thickness fluctuations for thicker films having high dislocation densities. We also demonstrate that the reflectivity of a heteroepitaxial system can be measured and modeled over an extended angular range, starting from grazing angles and continuing through the regions of Bragg scattering at higher angles. Disorder in epitaxial layers typically gives a mosaic line broadening transverse to the reflectivity and we show that transverse line shape considerations are crucial to these measurements.

The results of a high resolution x-ray scattering study of [001]ErAs epitaxial layers grown on [001]GaAs is presented. ErAs is pseudomorphic on GaAs for thicknesses below 70Å and, for thicker films, lattice relaxation is oberved concomitant with an Increase of the In-plane mosaic due to the formation of misfit dislocations. Above 300Å, the out-of-plane transverse scattering from the ErAs lattice planes Is no longer specular and further relaxation Is related to the out-of-plane mosaic. The ratio of elastic constants, C12/C11, Is determined to be 0.126 and the thermal expansion was measured. Thin film Interference oscillations are observed and modeled. ErAs/GaAs Is an Ideal system for x-ray scattering studies of lattice relaxation and structure in epitaxial layers. Films as thin as 20Å have been studied.