Scanning stage microscopes have traditionally been used to provide high resolution, large area photocurrent mapping of solar cells and detectors. This imaging method, while very useful in the characterization and quality control of solar cells, is unfortunately slow (image acquisition takes several minutes). This paper describes a confocal scanning beam MACROscope-Microscope which can image specimens from 25×25 μm up to 7.5×7.5 cm in size, a zoom factor of 3000, using reflected light, photoluminescence, and optical beam induced current in less than 10s. Resolutions range from 0.25 to 10 μ;m laterally and 0.5 to 300 pm axially depending upon whether microscope or MACROscope mode is used. This instrument can therefore be used to characterize and provide quick and efficient quality control for solar cells and detectors at a microscopic and macroscopic level.

A brief description of the MACROscope-Microscope is given. The MACROscope- Microscope's many abilities are highlighted by showing various reflected-light, photolhminescence and optical beam induced current images from CdZnS/CulnSe2 thin film solar cells and porous silicon devices.

We present a handy new method of optical investigation of thin semiconductor layers regardless of the substrate's composition and structure. The method was especially developed for the particular case of thin (˜ 1μm ) CdTe films obtained by means of electrochemical deposition on conducting glass for further solar cell applications. The procedure consists in transmission and reflection (or the transmission only) measurements under different thicknesses of the semiconductor layer and following semi-analytical treatment of the data. Finally we obtain the frequency dependencies of the real and imaginary parts of the refractive index for the semiconductor material of the layer.

In order to simulate the performance of the present day state-of-the-art multijunction solar cells in its entirety, an integrated electrical-optical model has been developed. The one-dimensional ab initio electrical model for the analysis of the transport properties of such devices can handle a very general semiconductor device structure where the material properties vary with position and the gap state properties with position and energy. The original semi-empirical optical model used takes into account both specular interference effects, and diffused reflectances and transmittances due to interface roughness. The latter are derived from angular-resolved photometric measurements and used as input parameters to the numerical programme. Comparison of the illuminated current density-voltage (J-V) characteristics, calculated on the basis of (a) a simple exponential absorption law and (b) the optical model, reveals an increase of ˜1 mA cm−2 in the short-circuit current and ˜8% in the cell conversion efficiency for case (b). Also the long wavelength quantum efficiency (QE) shows a marked improvement, while the blue QE decreases since proper account is taken of the absorption in the transparent conducting oxide and reflection from the device. The combined model is being applied to simulate the characteristics of wideband-gap-emitter-layer solar cells deposited in a three chamber conventional glow discharge reactor onto (i) highly textured SnO2 and (ii) weakly textured indium tin oxide substrates. The cells have been characterised experimentally by J-V and QE measurements. Preliminary results indicate that the integrated model matches the experimental J-V and QE data with a more realistic set of material parameters as compared to case (a).