Photoluminescence studies on thermal donors in boron- and aluminum-doped silicon.

Abstract

Photoluminescence (PL) spectroscopy of excitons bound to thermal donors (TD's) has been applied to probe the generation kinetics of TD's in boron- and aluminum-doped Czochralski-grown silicon. The results were compared with magnetic-resonance data on the development of Si-NL8 and Si-NL10 TD-related EPR spectra. The results of the PL study provide evidence that TD centers are generated very similarly, with regard to the original acceptor doping of the material. At the same time the removal of acceptors from their substitutional positions is clearly different with the aluminum atoms being removed much faster. Taken together, the results of the study indicate that the different TD-growth development in Al- and B-doped Czochralski-grown silicon as evidenced by EPR measurements should be attributed to different behavior of the Fermi-level position in these two materials rather than to genuine differences in the generation of TD centers. It is argued that such a conclusion supports the identification of both TD-related Si-NL8 and Si-NL10 EPR spectra with different charge states of basically the same thermal-donor center.