Electrical Properties of Mg-Implanted 4H-SiC

Because Al and B (elements of III group) in SiC are deep-level acceptors and these acceptors cannot reduce the resistivity of p-type SiC very much, Mg (element of II group) that may emit two holes into the valence band is investigated. A p-type 4H-SiC layer is obtained by 1800 degrees C annealing of the Mg-implanted layer, not by 1600 and 1700 degrees C annealing. It is found that a Mg acceptor level in 4H-SiC is too deep to determine the reliable density and energy level of the Mg acceptor using the frequently-used occupation probability, i.e., the Fermi-Dirac distribution function. Using the distribution function including the influence of the excited states of an acceptor, therefore, the density and energy level of the Mg acceptor can be determined to be approximately 1x10(19) cm(-3) and 0.6 eV, respectively. Judging from the Mg implantation condition, the obtained values are considered to be reliable.