Isoelectronic bound excitons in silicon: The role of deep acceptors

A recently discovered sample treatment technique which greatly enhances the intensities of the isoelectronic bound exciton luminescence lines in indium-doped silicon was applied to samples doped with the even deeper acceptor thallium. Many new isoelectronic bound exciton luminescence lines were observed, demonstrating the importance of the strongly attractive (for holes) acceptor central cell potential in binding these excitons. The striking similarities and differences of the two spectra are discussed.