INVESTIGATION OF THE OPTOELECTRONIC PROPERTIES OF CRYSTALLINE SILICON TEXTURED BY MASKLESS PLASMA ETCHING AT DIFFERENT IGNITION MODES

摘要

Plasma etch processes for dry, maskless micro-structuring of monocrystalline silicon at temperatures above 0 °C for effective light absorption as well as passivation properties are investigated with respect to photovoltaic applications. Focused on the ignition mode, silicon samples are etched by two different plasma procedures: for the first one the capacitively coupled power generator is solely used, and for the second one there is an additional inductively coupled power generator to increase the plasma density without simultaneously increasing the DC bias. Afterwards, an about 30 run thick Al_2O_3 layer is deposited on the structured surfaces in an atomic layer deposition process to passivate the samples. Using scanning electron microscopy, reflection measurements and quasi steady state photoconductivity measurements to determine the effective minority charge carrier lifetime, the results are analyzed and differences and advantages are discussed.