Interpretation of the electron capture by multiphonon emission at native levels in LPE gallium arsenide

Assuming a multiphonon capture mechanism, and on the basis of static coupling, the authors have performed a theoretical fitting of the temperature dependence of the electron capture cross section at A and B levels in LPE gallium arsenide. The effective number of phonons emitted and the Huang-Rhys factor used in the fitting were respectively p=32 and S=11.7 for A level and p=25 and S=5.03 for B level. In either case they were found to depend on the determination of the matrix elements involved in the transition. The use of the quantum defect wavefunction for the bound state and a coupling to optical phonons in the calculation of these matrix elements allowed a good fitting over the experimental temperature range. Furthermore they have not observed any contribution of radiative capture or Auger-assisted processes, in contrast to previous attempts which could not achieve fitting by the multiphonon mechanism alone.