OPTICAL-PROPERTIES OF QUASI-CRYSTALLINE APPROXIMANT BORON-RICH SOLIDS

The photoluminescence (PL) spectrum of a single crystal of beta-rhombohedral boron, which is a rhombohedral crystalline approximant of the icosahedral quasicrystal, has a peak around 1.14 eV. This is assumed to correspond to recombination between a hole in the intrinsic acceptor level originated from B-12 icosahedral cluster, and an electron in the highest trapping level. Thermal quenching of the PL intensity is analyzed by two activation processes, whose activation energies are 0.12 and 0.004 eV. The former is considered to be an escape process of an electron from the trapping level.