Crystalline phase destruction in silicon films by applied external electrical field and detected by using the laser spectroscopy

We studied the microcrystalline and nanocrystalline silicon thin films by means of Raman spectroscopy technique. The applied external electric field causes the changes in the electric dipoles’ orientations to compensate the external field, and migration the atom of impurities, such as hydrogen, and point defects. The Si-O dipoles play the most significant role because of electron affinity for oxygen. Phonon eigen-frequencies 480 cm-1 for amorphous silicon Raman spectra around and 520 cm-1 for crystalline TO and LO modes are varied in their energy positions because of wide spread in bonding variation for Si and O atoms, types of dipoles for different point defects and isotopic variations. It is assumed that the nanocrystals which have grain boundary with oxygen atoms incorporated into silicon were destroyed in their crystal structure by Si-O dipoles reorientations caused by applied field. The initial crystal orientation was (111). The incorporated oxygen atoms are adsorbed in determined places. Their position results the appearance of numerous dangling bonds which are multiplied by the electric field and create the deep cracks in crystals. The crystal order is damaged along the axis that is perpendicular to (111). It is supposed that the microcrystal is a fractal structure on 2D plane.