Papers by Author: J. Sadło

Abstract: n- and p-type 6H-SiC single crystals grown by PVT method using different charge materials – poly-SiC sinter or fresh SiC powder – have been studied. An open or closed seed backside during the growth processes have been applied. In the former, a distinct decrease backside etching of the seed was observed. Crystals have been extensively characterized with respect to their purity, quality and electrical properties using complex experimental methods. For the n-type boule an axially and radially homogeneous resistivity ~0.11 cm at 300 K was observed. Electrical properties of the p-type crystal, i.e., high room-temperature resistivity of 239 cm, were affected by compensation effects between residual donors (nitrogen and oxygen) and acceptors (mainly boron).

Abstract: Silver sodalite crystals with hydroxyl guest anion and silver loading higher than 7.9 per unit cell were investigated. EPR spectra of sodalite, recorded just afer g-irradiation at 77K, shows a 9-line, near isotropic signal with giso=1.987 and hyperfine splitting of 8.3 mT. The signal decays completely above 200K. We assign the multiplet to silver octamer Ag8 n+ cluster and tentatively postulate that the cluster charge is +7.