Using positron annihilation measurements the formation of thermal vacancies in highly As and P doped Si was observed. The vacancies started to form at temperatures as low as 650K and were mainly undecorated at high temperatures. Upon cooling the vacancies form stable vacancy-impurity complexes such as V-As3. A vacancy formation energy of 1.1eV, and a migration energy of 1.2eV, in highly-doped Si were determined. By associating these values with the vacancy-impurity pair, estimate of 2.8eV was obtained for the formation energy of an isolated neutral monovacancy in intrinsic Si.

Formation of Thermal Vacancies in Highly As and P Doped Si. V.Ranki, K.Saarinen: Physical Review Letters, 2004, 93[25], 255502