INTERBAND TRANSITIONS AND PHONON SPECTRA OF SI-DOPED B12P2

摘要

Optical absorption and FT Raman spectra of polycrystalline B12P2 prepared by CVD on silicon substrates are presented, The silicon content is rather high, and me assume that a ternary compound with the structure formula B-12(P-2)(1-x)(Si-2)(x) is formed, The absorption edge yields indirectly allowed transitions at 1.62, 1.80, 2.17, 2.46, and 2.75 eV, the energies of which are considerably lower than those reported by G. A. Slack et al. (1983, J. Phys. Chem. Solids 44, 1009) for pare B12P2. Six gap-state related transitions have ionization energies, which agree with those of electron traps in beta-rhombohedral boron, The number of one-phonon resonance frequencies agrees exactly with that predicted from group theory, The two-phonon spectra are quantitatively determined, Strong luminescence radiation superimposes the FT Raman spectrum, which differs qualitatively from that traditionally measured, This difference is explained by fluctuating distortions of the icosahedra related to the strong optical excitation of trapped electrons. (C) 1997 Academic Press. [References: 22]