Visible cathodoluminescence from Eu-implanted single- and polycrystal c-BN annealed under high-temperature, high-pressure conditions

Red and red/blue cathodoluminescence in the temperature range 12 to 300 K was obtained from single- and polycrystal cubic boron nitride bulk samples implanted with europium and annealed under high-temperature, high-pressure conditions. All observed radiative intra-4f electron transitions of Eu3+ can be assigned to transitions starting from the 5D0 level of Eu3+. Additionally, radiative 4fN−15d→4fN electron transitions related to Eu2+ were detected in the polycrystal c-BN specimens. The higher-resolution Stark level as well as the time-resolved cathodoluminescence spectroscopy suggest that the Eu ions occupy at least two different sites in the c-BN host.