Unstable displacement defects and hydrogen trapping in GaAs

Abstract

Defects produced by implantation of hydrogen into GaAs at 80 K have been investigated. Upon implantation, a predominant absorption band at 2029 cm Ϫ1 for As-H centers is observed. A 10-cm Ϫ1 full width at half maximum at 80 K for the band, and strong dependence of the frequency and bandwidth on measurement temperature, are indicative of bonding of hydrogen at displacement defects within the lattice. Results from annealing show loss of As-H centers between 180 and 250 K with an activation energy of 0.5Ϯ0.5 eV. Characteristics for As-H center annealing are compared to those reported previously for atomic displacement disorder in irradiated GaAs. Release of hydrogen from As-H bonds within thermally unstable damage regions is suggested to explain the annealing loss of As-H centers. An increase in absorption by Ga-H centers upon loss of As-H centers is attributed to retrapping of hydrogen on Ga neighbors of V As or on V As -As i pair defects.