Tellurium donors in silicon

Abstract

The electronic properties of chalcogens as dopants in silicon are discussed with emphasis on tellurium. Tellurium give rise to two dominant donor levels which have been studied by junction space-charge techniques, infrared absorption, and ESR. Both donor levels exhibit excited states (Rydberg series and multivalley split-off states) which are in agreement with those expected for singly and doubly charged centers, respectively. These results suggest that tellurium causes a double donor level in silicon. One of the donor states has been identified by ESR as ${\mathrm{Te}}^{+}$. Hyperfine interactions with the $I=\frac{1}{2}$ nuclei ${}_{}{}^{125}{}_{}{}^{}\mathrm{Te}$ and ${}_{}{}^{123}{}_{}{}^{}\mathrm{Te}$ as well as with ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ in the surrounding lattice have been observed. The ESR line shape due to the interaction with ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ suggests that the tellurium donor levels occupy substitutional sites. Photo-ESR clearly shows that both the ESR signal and the data obtained from junction space-charge techniques and infrared absorption measurements originate from the same center. From the excited states, temperature-independent ground-state binding energies of 198.8 and 410.8 meV, respectively, have been deduced.