Quasi-molecules of Sulphur in Silicon

The paper is concerned with the study of behavior of impurity centers of sulfur in silicon as a function of vapor pressure (P
s
) of sulfur during its diffusion doping. It was revealed that at low Ps, sulfur in silicon is in a state of individual substitution atoms. Following the vapor pressure (P
s
) ≥0,5 •10
⁵
Pa, the «quasi-molecules» consisting of two neighboring sulfur substitution centers - S
2
, start to assemble in the bulk of silicon, and at P
s
≥1•10
⁵
Pa, we are witnessing the occurrence of «quasi-molecules» that presumably consist of four sulfur substitution centers - S
4
. The concentration of both atomic centers and S
2
-type «quasi-molecules» tends to rise steadily as Ps increases. At the same time, the concentration of S
4
-type «quasi-molecules» first has risen (before the pressure has reached P
s
=2•10
⁵
Pa), and then fallen. It was revealed that in the presence of such S
4
-type «quasi-molecules» the sensitivity characteristics of the sample to various external influences substantially increased.