J. Dolensky

Low-Frequency Noise and Microplasma Analysis for c-Si Solar Cell Characterization

This paper brings the comparison of solar cell conversion efficiency and results from a noise spectroscopy and microplasma presence to evaluate the solar cell technology. Three sets of monocrystalline silicon solar cells (c-Si) varying in front side phosphorus doped emitters were produced by standard screen-printing technique. From the measurements it follows that the noise spectral density related to defects is of 1/f type and its magnitude. It has been established that samples showing low noise feature high-conversion efficiency. The best results were reached for a group solar cells with selective emitter structure prepared by double-phosphorus diffusion process.

Diagnostic methods of solar cells in dependence on temperature

This study is focused on testing methods determining quality of solar cells. Nowadays the development of solar cells is much faster and there is still necessary to increase their quality by removing causes of materials defects and also defects in a process of their production. Non-destructive methods are used for correct determination of defects by using of recombination effect of charge carrier in PN junction. Due to these methods can be the solar cell diagnosed and described. By using of various temperatures during the testing we can receive more objective results thanks to simulated operation conditions. Peltier cells are used for graditional change of temperature. Cooling system with liquid nitro - LN2 is used to reach the very low temperature. Diagnostic and testing methods described in this study are based on emission of light and the recombination processes in PN junction. It is especially electroluminescence and photoluminescence method. For comparison it is used the observation of emitted light from microplasma method. Described methods detect materials and process defects due to use of lownoise and very sensitive CCD camera.

Comparisons of noise spectroscopy analyze and microplasma noise sources

As it was the mechanical noise used for diagnostic of machine in the past, the electronic noise can be used as diagnostic tool for detection defects in electronical devices and systems in the future. This paper deals with comparisons of noise spectroscopy and detection of microplasma noise sources in the three new type of solar cells G1, G3 and G5. When high electric is applied to PN junction with some technological imperfections like dislocation in PN junction or crystal-grid defect causing non-homogeneity of parameters it produces in tiny areas of enhanced impact ionization called microplasma. It can leads onwards to deterioration in quality or to destruction of PN junction. Microplasma produced noise, which has random spectrum in frequency range. Microplasma noise is measurable even before the creation of light emissions. Due to the comparisons microplasma detection with noise characteristic can full analyzed solar cell.