The evolution of electrical activation with annealing time, in B+-implanted (5 x 1014/cm2, 50keV) material, was studied as a function of annealing temperature. Electrical activation yields of 15 to 30% were observed after annealing for 2s at temperatures of more than 550C. When the annealing time was increased from 2 to 900s, it was observed that the electrical activation variation depended upon the temperature. At temperatures of between 550 and 700C, it decreased towards an equilibrium level. At temperatures of between 700 and 800C, it decreased during the first few minutes and then increased again. At temperatures below 550C, or above 800C, it increased continuously. In order to explain the carrier removal which was observed during annealing at 550 to 800C, it was proposed that metastable acceptor centers formed during B+ implantation and/or during the early stages of annealing. The interaction of Si self-interstitials with these centers led to their neutralization and/or dissociation; thus decreasing the carrier concentration.

J.P.De Souza, H.Boudinov: Applied Physics Letters, 1995, 66[23], 3173-5