Deep states of Pt, Ir, and Os in Silicon Carbide

Abstract

Band gap states of platinum, iridium, and osmium in 4H silicon carbide (SiC) are investigated with Deep Level Transient Spectroscopy (DLTS). A definite chemical assignment of band gap states to Pt, Ir, and Os was achieved by means of the radiotracer principle: the radioactive isotope 188Pt serves as a probe atom providing an unambiguous finger print with its well know half‐life. Characteristic concentration changes traced by DLTS lead to a definite assignment of deep levels to the specific element. Pt, Ir, and Os are involved in the observed decay chain: 188Pt decays with a half‐life of 10.2 d to 188Ir which itself further decays to the stable 188Os with a half‐life of 1.7 d. Subsequent DLTS measurements reveal two Pt‐related band gap states: a double‐acceptor at 0.81 eV and a single acceptor at 1.46 eV below the conduction band edge EC. Iridium possesses one acceptor‐like state (EC − 0.82 eV) in 4H‐SiC. An acceptor state at EC−0.41 eV and a donor state 0.31 eV above the valence band edge EV to osmium. Fu...