FORMATION OF 4 NEW SHALLOW EMISSIONS IN MN-IMPLANTED GAAS GROWN BY MOLECULAR-BEAM EPITAXY HAVING EXTREMELY LOW CONCENTRATION OF BACKGROUND IMPURITIES( ION)

Mn+ ions were implanted into ultrapure GaAs layers grown by molecular beam epitaxy. 2 K photoluminescence revealed that in addition to the w ell-established Mn-related deep acceptor emission at approximately 1.4 1 eV, four new shallow emissions denoted by (Mn-degrees, X), ''G'', '' H'', and (D, A)2 are formed in the near band edge when the Mn concentr ation [Mn] exceeds 3 X 10(16) cm-3 . Both ''G'' and ''H'' exhibit no e nergy shift with growing [Mn] up to 1 X 10(19) cm-3. In contrast, for shallow acceptor- (such as C) doped GaAs with extremely low background concentrations of donor impurities, a series of [g-g]-like energy lev els, which present strong energy shifting with increasing acceptor con centration, are universally formed. These results show that pairs betw een deep Mn acceptors do not produce such [g-g] like energy levels.