Masako Hirata

The Interactions of Point Defects with Impurities in Silicon

The minority carrier lifetime in gamma-irradiated silicon crystals was studied. In F. Z. n type crystals containing phosphorous, arsenic, antimony or bismuth, there are two annealing stages in the temperature range 100–280°C and in both stages there is strong dependency of activation energies E a and frequency factors on the atomic size of the impurity. The relationship between E a and covalent radii of the impurity atom can be experimentally expressed in linear functions. The defect which anneals in the lower temperature stage is a complex of donor atoms associated with a vacancy type defect. Si-E center anneals in the higher temperature stage and the values of activation energies completely agree with those obtained by Watkins et al. in their experiments of reorientation of donor-vacancy axis. The defects of both stages are considered to migrate to the sinks of oxygen after jumps of about 10 5 . It is very interesting to note that this study shows only one example of an impurity atom which moves with a ...

EFFECT OF IMPURITIES ON THE ANNEALING BEHAVIOR OF IRRADIATED SILICON.

The effect of impurities on the annealing behavior of irradiated silicon was studied through an investigation of isothermal annealing of minority carrier lifetime in silicon crystals containing phosphorus, arsenic, antimony, or bismuth in the temperature range 100°–180°C. The activation energy for the annealing of vacancy‐impurity complex increased with increasing atom size of the dopant. The values are 0.93, 1.27, 1.84, and 2.22 eV. The frequency factor was also found to be dependent on impurity as well as concentration of the complex. The variation of these parameters is discussed in terms of the lattice strain associated with impurity atoms which have a larger covalent radius than silicon.

Vacancy Capture Radii of Impurity Atoms in Silicon

The interaction of a vacancy with group V impurity atoms in silicon has been studied. Vacancy capture radii were compared among group V impurity atoms As, Sb and Bi. Though absolute values are not given at this time, it is interesting to note the trend that the vacancy capture radius decreases as the covalent radius of impurity atom increases.