Evidence for a substitutional Mg acceptor level in silicon.

Abstract

Among group-II impurities in silicon, Be and Zn result in substitutional acceptors while Mg has been known to cause only interstitial donor levels. We have diffused Mg into ${n}^{+}$-p silicon diodes and found a number of hole levels in the lower half of the band gap of silicon. The dominating level in most samples, named the A level, has been studied in detail. Using space-charge techniques, thermal emission rates, the temperature dependence of capture cross sections, and photoionization cross sections have been measured. The experimental results are best explained if this level is considered to be an acceptor with an energy position of ${E}_{v}$+0.34 eV. There are sufficient grounds to suggest that this could be the missing substitutional Mg acceptor level in silicon.