Theoretical investigation of incomplete ionization of dopants in 6H-SiC metal-oxide-semiconductor capacitors

The effect of incomplete ionization of dopants on the capacitance-voltage ( C-V) characteristics in 6H-SiC metal-oxide-semiconductor (MOS) capacitors h as been investigated. The present exploration is based on the one-dimension al numerical solving of Poisson's equation using the finite-difference meth od with a nonuniform mesh size. The results obtained from this approach are in good agreement with the first analytical results reported by Bouillon a nd Skotnicki in the case of indium impurities in silicon [IEEE Electron Dev ice Lett. 19, 19 (1996)]. For p-type 6H-SiC material, characterized by deep er doping impurity energies (principally aluminum and boron), simulations p redict the occurrence of a "kink effect" on the C-V curves, depending on te mperature and doping level, that could lead to experimental errors in the e xtraction of MOS device parameters, including effective doping level, inter face trap density, and fixed oxide charge. (C) 1999 American Institute of P hysics. [S0021-8979(99)03616-6].