Deep levels in cw laser-crystallized silicon thin films

Abstract

Electronic defect levels in cw laser-crystallized silicon thin films have been measured with deep level transient spectroscopy. Polycrystalline silicon thin films were deposited on thermal oxides over single-crystal silicon and crystallized with a scanning cw Ar-ion laser. Hole-emission spectra, recorded on inverted metal-oxide-silicon capacitors with p-type conductivity, reveal a continuous distribution of deep levels in the lower-half of the silicon band gap. There is no evidence of discrete energy levels with densities ⩾1×1014 cm−3, and its proposed that defect levels at the Si-SiO2 interface are a major source of emission centers in crystallized silicon thin films, along with grain boundaries which can also contribute a continuous defect distribution.