ELECTRONIC-STRUCTURE OF BOND-CENTERED HYDROGEN AND MUONIUM IN III-V COMPOUND SEMICONDUCTORS - ABINITIO CLUSTER CALCULATIONS

The molecular orbital model for bond-centred hydrogen or muonium in the III-V compound semiconductors is developed with the help of ab initio cluster calculations. The influence of the loss of symmetry in going from the elemental (group IV) to the compound (III-V) materials on the electronic structure is studied. The equilibrium configurations, potential energy surfaces and electronic structures of hydrogen or muonium near the bond-centred site in GaAs, GaP and InP are calculated at the ab initio HF level in the clusters Ga4As4H18 and the corresponding one for GaP and InP using a split-valence basis set and ab initio pseudopotentials for the core orbitals. First results of the calculations using a large Ga22As22H42 cluster are discussed. Preliminary results for InP indicate that ionization of the bond-centre defect may be considerably easier than in the other III-V compounds, which would explain why mu-SR-signals corresponding to the neutral Mu* state have not been detected in this material.