A study was made of thin film silicon solar cells with in situ doped epitaxial emitter deposited on Si substrate by rapid thermal chemical vapour deposition. High-resolution transmission electron microscopy images revealed that low temperature Si epitaxy growth induces mechanical twins at the junction interface. The presence of the twins alters the orientation of the crystal planes, increased the optical path length of light within the epitaxy film and improves the optical absorption. On the other hand, these twins appeared to be the main cause for material-induced shunting at the p-n junction. Photoluminescence mapping indicated that lower growth temperature results in better interface quality.

Optical Absorption Enhancement by Mechanical Twins Grown using Low Temperature Silicon Epitaxy. D.Lai, Y.H.Tan, C.S.Tan: Energy Procedia, 2011, 8, 238-43