Europium Induced Deep Levels in Hexagonal Silicon Carbide
Silicon carbide (SiC) was investigated for deep band gap states of europium by means of deep level transient spectroscopy (DLTS). The knowledge of the properties of optoelectrically active impurities or defects is essential for a detailed understanding of the energy-transfer process resulting in the observable excitations . SiC-samples of the polytypes 4H as well as 6H are ion-implanted by different europium- isotopes in order to obtain a chemical identification of the characterized energy levels. Here the concentration sensitivity of the DLTS is applied to observe the elemental transmutation of the incorporated radioactive tracer atoms 146Eu (t1/2=4.51 d) and 147Eu (t1/2=24.6 d). DLTS on samples implanted with stable Eu-ions (153Eu) was carried out for comparison and manifestation of the results. From these studies 5 Eu-related deep band gap levels are established: in 4H-SiC two levels at EV+0.86(2) eV and EC−0.47(2) eV, and in 6H-SiC three levels at EV+0.88(2) eV, EC−0.29(2) eV and EC−0.67(2) eV.
Robert P. Devaty, David J. Larkin and Stephen E. Saddow
G. Pasold et al., "Europium Induced Deep Levels in Hexagonal Silicon Carbide", Materials Science Forum, Vols. 527-529, pp. 659-662, 2006