ATOMIC-STRUCTURE OF SHALLOW ACCEPTOR-HYDROGEN AND DONOR-HYDROGEN COMPLEXES IN GAAS

The microscopic structures of an interstitial hydrogen atom in p- and n-type GaAs are determined using an ab initio pseudopotential method. For Be impurities substituting Ga ions, hydrogen sitting at the bond-center site more strongly bonds to one of the neighboring As atoms than to the acceptor, while a direct donor-H bond takes place in Si-doped samples. This character of hydrogen bonding of passivated Si-H complexes is similar to that of Si-H bonds in n-type Si. For group VI donors such as S, hydrogen strongly interacts withthe neighboring host Ga breaking a donor-Ga bond.