Silicon with an increased content of monoatomic sulfur centers: Sample fabrication and optical spectroscopy

The effect of the high-temperature heating (at 1340$^\circ$C) of sulfur-doped silicon samples and their subsequent quenching is studied. The results of such a treatment are analyzed on the basis of Hall-effect data obtained in the temperature range $T$ = 78–500 K. It is shown that the heating duration strongly affects the relative concentrations of different types of deep sulfur-related centers. At comparatively short heating durations of $t$ = 2–10 min, the concentration of quasi-molecular S$_2$ centers and $S_X$ complexes substantially decreases, whereas the density of monoatomic S$_1$ centers grows. At the same time, the heating of a sample is accompanied by a monotonic decrease in the total concentration of electrically active sulfur over time. The results obtained make it possible to give recommendations concerning the optimal conditions for the fabrication of samples with a high concentration of S$_1$ centers. The absorption spectra of the samples show that the method is promising for the observation of a number of quantum-optical effects involving deep S$_1$ donors in silicon.