Deep level defect study of molecular beam epitaxially grown silicon films

Abstract

We report the result of the study on the electrically active deep level defects in Si films grown by molecular beam epitaxy. A deep level defect at Ec−0.58 eV is consistently obtained for samples grown on substrates with purposely contaminated surfaces. The observed defects are all located within 3000–5000 Å of the epilayer-substrate interface with concentrations in or below 1014 cm−3 range. Secondary ion mass spectroscopic study results indicate the correlation between the substrate surface residual carbon concentration and the observed defect concentration. These defects appear to be higher order defects rather than the single level defects, as evidenced by the asymmetry of the deep level transient spectra. For samples grown on the substrates cleaned using an established surface cleaning method, no deep level defects within the detection limit (∼1012 cm−3 in our case) are observed.