The present work shows results on elemental distribution analyses in Cu(In,Ga)Se2 thin films for solar cells performed by use of wavelength-dispersive and energy-dispersive X-ray spectrometry (EDX) in a scanning electron microscope, EDX in a transmission electron microscope, X-ray photoelectron, angle-dependent soft X-ray emission, secondary ion-mass (SIMS), time-of-flight SIMS, sputtered neutral mass, glow-discharge optical emission and glow-discharge mass, Auger electron, and Rutherford backscattering spectrometry, by use of scanning Auger electron microscopy, Raman depth profiling, and Raman mapping, as well as by use of elastic recoil detection analysis, grazing-incidence X-ray and electron backscatter diffraction, and grazing-incidence X-ray fluorescence analysis. The Cu(In,Ga)Se2 thin films used for the present comparison were produced during the same identical deposition run and exhibit thicknesses of about 2 μm. The analysis techniques were compared with respect to their spatial and depth resolutions, measuring speeds, availabilities, and detection limits.

The influence of the transparent conducting oxide (TCO) topography was studied on the performance of a silicon oxide intermediate reflector layer (IRL) in a-Si/μc-Si tandem cells, both experimentally and by 3-D optical simulations. Therefore, cells with varying IRL thickness were deposited on three different types of TCOs. Clear differences were observed regarding the performance of the IRL as well as its ideal thickness, both experimentally and in the simulations. Optical modeling suggests that a small autocorrelation length is essential for a good performance. Design rules for both the TCO topography and the IRL thickness can be derived from this interplay. Index Terms-3-D rigorous optical modeling, a-Si/μc-Si, intermediate reflector, micromorph, solar cells, transparent conducting oxide (TCO). I. INTRODUCTION AND BACKGROUND A S THE demand for affordable clean energy grows, amorphous silicon (a-Si) / microcrystalline silicon (μc-Si) tandem solar cells are an interesting technology, as it combines nontoxic and abundant materials with a low temperature/low cost process. However, the conversion efficiency of these de-Manuscript

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The composition of silicon oxynitride (SiO x N y :H) films deposited by electron cyclotron resonance chemical vapour deposition (ECR-CVD) was analysed by ion beam techniques, heavy-ion elastic recoil detection analysis (HI-ERDA) with 150 MeV 86 Kr ions and Rutherford backscattering spectroscopy (RBS) with 1.4 MeV 4 He ions. The results were compared with energy dispersive X-ray analysis (EDX) and Auger electron spectroscopy (AES). Since HI-ERDA provides absolute atomic concentrations of all film components including hydrogen with a sensitivity of at least 0.005 at% the data from this method were used as a quantitative reference to assess the applicability of RBS, EDX and AES to the analysis of silicon oxynitrides. For each of these techniques the comparison with HI-ERDA allowed a discussion of the different sources of error, especially of those causing systematic deviations of the measured concentration values. A novel approach to determine from RBS spectra also the hydrogen concentrations appeared to be applicable for hydrogen levels exceeding 2 at%. Furthermore, it is shown that the film density can be determined from the HI-ERDA results alone or in combination with single-wavelength ellipsometry.

Thin Ca films were evaporated on Si(111) under ultrahigh vacuum conditions and annealed in the temperature range 200-650• C. The interdiffusion of Ca and Si was examined by ex situ Auger depth profiling. In situ monitoring of the Si 2p core-level shift by x-ray photoelectron spectroscopy was employed to study the silicide formation process. The formation temperature of CaSi 2 films on Si(111) was found to be ∼350 • C. Epitaxial growth takes place at ≥400 • C. The morphology of the films, observed by atomic force microscopy, was correlated with their crystallinity as analysed by x-ray diffraction.