DEACTIVATION IN HEAVILY ARSENIC-DOPED SILICON

We have combined ab initio calculations with a general statistical the ory to predict the properties of heavily arsenic-doped silicon. Althou gh we find that a lattice vacancy surrounded by four arsenic (VAs4) is the dominant deactivating complex at high arsenic concentrations in e quilibrium, vacancy clusters with fewer arsenic neighbors are present in significant quantities. These smaller complexes are essential not o nly to the establishment of equilibrium, since SiAs4 clusters are extr emely rare, but can also explain deactivation even if VAs4 formation i s kinetically inhibited. This suggests that materials with similar ars enic concentration and deactivation fractions can have different micro scopic states, and therefore behave differently in subsequent processi ng. Good agreement is found between theory and experiment for the elec tronic concentration as a function of temperature and total arsenic co ncentration. We also show that for low arsenic concentrations, full ac tivation is the equilibrium condition. (C) 1998 American Institute of Physics.