Infrared absorption cross sections, and oscillator strengths of interstitial and substitutional double donors in silicon

Abstract

Infrared absorption cross sections and corresponding oscillator strengths of several intracenter transitions of double donors in silicon, interstitial magnesium (Mg; group IIA) and substitutional chalcogens (Ch = S; Se; group VI), were determined for impurity densities in the ranges $1\ifmmode\times\else\texttimes\fi{}{10}^{14}--1.6\ifmmode\times\else\texttimes\fi{}{10}^{15}\phantom{\rule{0.16em}{0ex}}\mathrm{atoms}/\mathrm{c}{\mathrm{m}}^{3}$ for Mg and $2\ifmmode\times\else\texttimes\fi{}{10}^{13}--2\ifmmode\times\else\texttimes\fi{}{10}^{16}\phantom{\rule{0.16em}{0ex}}\mathrm{atoms}/\mathrm{c}{\mathrm{m}}^{3}$ for chalcogens. The concentrations of electrically active atomic and diatomic donor centers were derived from the Hall effect measurements. The experimental integrated cross sections were obtained from low-temperature impurity absorption spectra. The oscillator strengths of related donor transitions were derived and compared with those for shallow single donors in silicon, both determined experimentally and predicted theoretically. The transitions of oscillator strengths of double donors follow the decreasing trend with decreasing radius of donor ground states and increasing an impurity binding energy.