The effects of oxygen and defects on the deep-level properties of Er in crystalline Si

Abstract

We have investigated the electronic properties of Er in crystalline Si using deep-level transient spectroscopy and capacitance-voltage measurements. Erbium was incorporated by ion implantation in a p+-n junction structure. In order to explore the role of oxygen and defects some samples were coimplanted with O and the annealing behavior of the deep-level spectra was explored in the temperature range 800–1000 °C for annealing times ranging from 5 s to 30 min. We show that O-codoping produces large modifications in the Er-related deep-level spectra and, in particular, a promotion from deep to shallow levels, thus enhancing the donor behavior of Er in Si. For erbium implanted in pure crystalline Si the spectrum is dominated by deep levels arising from Er-defect complexes which are easily dissociated upon thermal annealing. In O-coimplanted samples the formation of Er-O complexes with a characteristic level at EC−0.15 eV is observed. These complexes form upon thermal annealing and are stable up to 900 °C. These results are presented and possible implications for our current understanding of the mechanisms of Er photoluminescence in Si are discussed.