HOLE TRAPPING BY BORON ATOMS IN SILICON AT LOW TEMPERATURES.

Results are given of a study of the hole lifetime tau in Si:B as a function of the temperature T (2-18 degree K) and the trapping center concentration n (10**1**3-10**1**5 cm** minus **3). For N greater than 10**1**4 cm** minus **3, there was found to be a considerably weaker temperature dependence of tau at T less than 4 degree K. In samples with N similar 10**1**5 cm** minus **3, tau was almost independent of the temperature below 10 degree K, and the dependence of tau on N was also much weaker. A qualitative interpretation of the experimental results is given, based on a simple model in which trapping is regarded as localization of a free carrier in a potential well attached to the impurity.