ROLE OF THE EL2 CENTER ON THE FORMATION OF METASTABLE HYDROGEN-RELATED DEFECTS (M3 M4) IN N-GAAS/

Hydrogen-related metastable defects (M3/M4) in n-GaAs were studied in relation to the EL2 center We found that the M3/M4 defects were observ ed only in the crystals containing the EL2 center in the as-grown stat e after exposure to a hydrogen plasma. The EL3 level, which was tentat ively assigned as off-center oxygen, could not be responsible for the formation of the M3/M4 defects. It was speculated that both diffused h ydrogen and the pre-existing arsenic antisite or its related defects w ere responsible for the formation of the M3/M4 defects. A quantitative analysis with the samples exposed to atomic hydrogen showed that the M4 defect consisted of two different configurations. A metastable comp onent of the M4 defect coupling with the M3 defect was nor formed or l atent in the as-irradiated state at room temperature. After bias annea ling at higher temperatures. such as 420 K. the M3/M4 couple was forme d.