Electrical characterization of deep levels in n-type GaAs after hydrogen plasma treatment

Deep level transient spectroscopy (DLTS) and Laplace-DLTS (L-DLTS) have been used to investigate defects in an n-type GaAs before and after exposure to a dc hydrogen plasma (hydrogenation). DLTS revealed the presence of three prominent electron traps in the material in the temperature range 20-300 K. However, L-DLTS with its higher resolution enabled the splitting of two narrowly spaced emission rates. Consequently four electron traps at, E-C-0.33 eV, E-C-0.36 eV, E-C-0.38 eV and E-C-0.56 eV were observed in the control sample. Following hydrogenation, all these traps were passivated with a new complex (presumably the M3), emerging at E-C-0.58 eV. Isochronal annealing of the passivated material between 50 and 300 degrees C, revealed the emergence of a secondary defect, not previously observed, at E-C-0.37 eV. Finally, the effect of hydrogen passivation is completely reversed upon annealing at 300 degrees C, as all the defects originally observed in the reference sample were recovered. (C) 2011 Elsevier B.V. All rights reserved.