Ab. Chen et P. Srichaikul, SHALLOW DONOR LEVELS AND THE CONDUCTION-BAND EDGE STRUCTURES IN POLYTYPES OF SIC, Physica status solidi. b, Basic research, 202(1), 1997, pp. 81-106
This study focuses on the calculation of conduction band edge structur
es and nitrogen (N) donor levels in four polytypes of SiC: 3C, 2H, 4H,
and 6H. A band-structure-based theory and a model potential are devel
oped for the donor level calculation. A hybrid pseudo-potential and ti
ght-binding Hamiltonian is used to obtain a set of comprehensive band
structures for these four polytypes by incorporating useful experiment
al information in the band-structure calculation. The conduction band
edge wave functions derived from these band structures and several set
s of theoretical and experimental effective masses are then used to st
udy the various effects on the donor level, which include anisotropic
masses, central cell potential correction, conduction band edge wave f
unctions, and intervalley coupling. With suitable sets of effective ma
sses, the calculated donor energies agree semi-quantitatively with tho
se deduced from experiments. The site dependence of the donor energies
in 4H and GH is found to be dominated by the conduction band wave fun
ctions and the intervalley coupling.