Electron Emission from the Electronic States of Oxygen Precipitates in Oxygen-Implanted Silicon

Defect structure and electric properties of n-type silicon samples subjected to multienergy oxygen implantation and subsequent multistage thermal treatments at different high temperatures and durations are investigated with the help of transmission electron microscopy (TEM), capacitance-voltage (C(V)), and deep level transient spectroscopy (DLTS) techniques. Well spatially separated layers in the depth consisting of three predominant types of defects-threading dislocations (TDs), oxygen precipitates (OPs) together with diverse extended structural defects and OPs only-are observed with TEM. While the properties of DLTS spectra from the layer with TDs coincide well with dislocation-related ones reported in numerous previously published articles, the spectra from the OP layer are found to show unusual distinct property: the low-temperature tail of DLTS peak does not or very weakly depend on the rate window. A simplified semiquantitative model is proposed based on a big positive charge of OP layer revealed from C(V) measurements. The model explains the unusual property to be due to an increase of the Coulomb-like attractive potential upon electron emission from the electronic states of the OPs giving rise to logarithmic emission kinetics.