Z1/2- and EH6-Center in 4H-SiC: Not Identical Defects ?
|Periodical||Materials Science Forum (Volumes 717 - 720)|
|Main Theme||Silicon Carbide and Related Materials 2011|
|Edited by||Robert P. Devaty, Michael Dudley, T. Paul Chow and Philip G. Neudeck|
|Citation||Bernd Zippelius et al., 2012, Materials Science Forum, 717-720, 251|
|Online since||May, 2012|
|Authors||Bernd Zippelius, Alexander Glas, Heiko B. Weber, Gerhard Pensl, Tsunenobu Kimoto, Michael Krieger|
|Keywords||Charge State, Deep Level Transient Spectroscopy, DLTS, EH6/7, Intrinsic Point Defects, Poole-Frenkel Effect, Z1/2|
Deep Level Transient Spectroscopy (DLTS) and Double-correlated DLTS (DDLTS) measurements have been conducted on Schottky contacts fabricated on n-type 4H-SiC epilayers using different contact metals in order to separate the EH6- and EH7-centers, which usually appear as a broad double peak in DLTS spectra. The activation energy of EH6 (EC - ET(EH6) = 1.203 eV) turns out to be independent of the electric field. As a consequence, EH6 is acceptor-like according to the missing Poole-Frenkel effect. Therefore, it can be excluded that the EH6-center and the prominent acceptor-like Z1/2-center belong to different charge states of the same microscopic defect as theoretically suggested. It is proposed that EH6 is a complex containing a carbon vacancy and another component available at high concentrations. The activation energy of EH7 (EC - ET(EH7) = 1.58 eV) has been evaluated indirectly by fitting the DLTS spectra of the EH6/7 double peak taking the previously determined parameters of EH6 into account.