ELECTRIC-FIELD-ENHANCED EMISSION FROM RADIATION-INDUCED HOLE TRAPS INP-GAAS

The electric field dependence of the emission rates of two radiation-i nduced hole traps in epitaxially grown p-GaAs, H beta 4 (E(v) + 0.2 eV ) and H beta 5 (E(v) + 0.3 eV), was studied using deep-level transient spectroscopy (DLTS). Both defects exhibit a significant emission enha ncement at electric fields above 5 x 10(4) V cm(-1), with the enhancem ent being much more pronounced for H beta 5. Neither of the two defect s shows an emission enhancement that is characteristic for a Coulombic well. When modelling the experimental results according to the Poole- Frenkel distortion of a square well, the H beta 4 can be adequately pr esented by a well with radius 10-20 Angstrom, which is typical of the potential range of a point defect. Using the same formalism, however, the H beta 5 has to be represented by extraordinary wide wells with ra dii of 35 Angstrom and 162 Angstrom at low- and high-field conditions, respectively. We conclude that the shape of the H beta 5 potential we ll changes with increasing electric field.