Boron and aluminium doping in SiCand its passivation by hydrogen

Abstract

Extensive calculations regarding the formation energy of interstitial hydrogenand hydrogen-vacancy complexes in different charge states have been carriedout using the local density approximation to ab initio densityfunctional theory with a plane-wave basis and norm-conserving pseudopotentialson supercells of cubic (3C) SiC. Based on these results the hydrogenconcentration of as-grown or H-plasma treated SiC is estimated and its effecton the net carrier concentration is given. Incorporation of B and Al in orwithout the presence of hydrogen has been investigated in hexagonal (4H) SiCsupercells. The possible origins of the shallow and deep boron acceptors isdiscussed. It is found that the presence of boron promotes hydrogenincorporation during growth in the form of passive B + Hcomplexes. The same is not true for Al. If Al + H complexes areformed (say, after H-plasma treatment), the structure of this complex isdifferent from that of the B + H complexes. The calculateddifference between the dissociation energies is 0.9 eV.