Radiotracer investigation of a deep Be-related band gap state in 4H-SiC

One Be-related deep level in the band gap of 4H-SiC was identified by radio tracer deep level transient spectroscopy (DLTS). The radioactive isotope Be -7 was recoil implanted into p-type as well as n-type 4H-SiC for these radi otracer experiments. DLTS spectra were taken repeatedly during the elementa l transmutation of Be-7 to Li-7. In the case of p-type 4H-SiC, they exhibit one peak of time-dependent height. Its concentration decreases with the ha lflife of the nuclear decay of Be-7 (T-1/2=53.3 d). Thus, this level at 1.0 6 eV above the valence band edge is identified as Be-related. In n-type 4H- SiC, neither Be- nor Li-correlated deep levels have been found in the inves tigated part of the band gap within the measurement accuracy. (C) 2001 Amer ican Institute of Physics.