Hole trapping by boron atoms in silicon at low temperature

The results of an investigation into the hole lifetime tau in relation to the temperature T (2-18 K) and the concentration of the capture centres N (1013 - 1015 cm-3) are presented. At N < 1014 cm-3 a considerable weakening of the tau temperature dependence at T < 4 K was observed. In samples with N approximately 1015 cm-3 tau was practically temperature independent below 10 K; the tau dependence on N then also weakened considerably. A qualitative interpretation of the experimental data is given on the basis of a simple model, in which the capture process is considered as free carrier localization in a potential well associated with an impurity