DONOR FORMATION IN SILICON OWING TO ION-IMPLANTATION OF THE RARE-EARTH-METAL ERBIUM

Schottky diodes in n- and p-type silicon, implanted with erbium and subsequently annealed at 900°C were characterized with capacitance-voltage (CV) and deep level transient spectroscopy (DLTS) techniques. The implanted samples showed an excess donor concentration with a depth profile similar to an erbium concentration profile, measured with secondary ion mass spectroscopy (SIMS). The peak concentration, however, is one order-of-magnitude below the estimated erbium peak concentration. DLTS measurements yielded one dominant donor-like electron trap in an n-type sample, with an activation energy of 0.266 eV and a depth profile similar to the CV profile. The peak concentration, however, is 1.5 orders-of-magnitude below that of the CV profile. From the consistency of the DLTS depth profile's peak position with that of the CV and SIMS depth profiles it is concluded that the measured activation energy is a reasonable estimate of the trap's Gibbs free energy.