Structural defects and photoluminescence of epitaxial Si films grown at low temperatures

Silicon layers grown by low-temperature Electron Cyclotron Resonance Chemical Vapour Deposition (ECR-CVD) were investigated using photoluminescence (PL) and defect etching. Different forms of etch pits could be observed using Scanning Electron Microscopy. The densities of the etch pits and the intensities of defect-related PL bands are compared. A correlation between two kinds of elliptical etch pits, two PL peaks and the impurity content was found. One of these PL peaks has an energy of 903 meV, usually attributed to the so-called rod-like defects. The orientation of the related etch pits is, however, not consistent with the orientation of rod-like defects. Possible explanations for this behaviour are discussed.