The dipole moments of H2, HD and D2 molecules and their concentrations in silicon

The relative strengths of infrared active modes of H-2, HD and D-2, present as H-2-O-i centres (v(1) and v(2)), or isolated molecules (v(3)) in Si pre-heat treated at 1300 degrees C in a 50 : 50 mixture of Hz and D-2 gases are reviewed. The effective charges eta(nu(1HH)) and eta(nu(2HH)) are equal to eta(nu(1DD)) and eta(nu(2DD)), respectively, but eta(nu(3HH)) = 0.08e is larger than eta(nu(3DD)) = 0.05e. The relative strengths of the three HD modes are smaller than expected by a factor of similar to 3. Possible reasons for this discrepancy, including isotopic exchange, are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.