Excitation photocapacitance study of EL2 in n-GaAs prepared by annealing under different arsenic vapor pressures -: art. no. 033705

The excitation photocapacitance method was applied to n-GaAs:Te (n=4x10(16) cm(-3)) prepared by annealing under various excess arsenic vapor pressures. By changing the primary excitation photon energies, the emission spectra for the EL2(0)-->EL2(+) and EL2(+)-->EL2(++) transitions were determined. Considering the electron capture processes of the valence band (VB)-->EL2(+) (0.67 eV) and VB-->EL2(++) (0.47 eV) at 77 K, the Frank-Condon shifts (d(FC)) of the annealed GaAs crystals were determined for the EL2(+) level on the basis of the configuration coordinate model. It was shown that the lattice relaxation around the EL2 level is larger under arsenic-poor conditions, and thus it is considered that arsenic vacancies are closely related with the atomic configuration of the EL2 defect, in combination with excess arsenic defects. (C) 2005 American Institute of Physics.