Deep-level photoluminescence emission in heavily Be-doped CBE-grown InP: an explanation of low Be acceptor activity

A thorough photoluminescence (PL) investigation of heavily Be-doped (up to a maximum of approximately 3*1019 atoms/cm3) chemical beam epitaxy (CBE) grown InP layers showed the presence of two prominent emissions related to Be, one involving simple isolated Be acceptors (BeIn-) and the other a deep-level (DL) band behaving like a pseudo donor (D)-acceptor (A) pair-like transition. From their identical values of activation energies for luminescence quenching ( Delta E approximately 40+or-2 meV), the participation of a simple BeIn- acceptor (A) and a deep donor (D) of the type (BeIn--Bei+)+ (where Bei stands for a doubly positively charged interstitial Be) have been predicted for the pseudo D-A pair of the DL emission. The possible presence of such centres is suggested as an explanation for the observed abnormally low acceptor efficiency (only 20 to 25%) of Be when doped heavily in InP.