The electric field dependence of the emission rates of 2 irradiation-induced hole traps in epitaxially grown p-type material was studied. The traps were H4 (Ev + 0.2eV) and H5 (Ev + 0.3eV), and were studied by using deep-level transient spectroscopy. It was found that both defects exhibited a significant emission enhancement at electric fields of more than 5 x 104V/cm; with the enhancement being much more pronounced in the case of H5. Neither of the defects exhibited an emission enhancement that was characteristic of a Coulombic well. Upon analyzing the experimental results in terms of a Poole-Frenkel distortion of a square well, H4 could be adequately represented by a well with a radius of 1 to 2nm. This was typical of the potential range of a point defect. However, within the same formalism, H5 had to be represented by extraordinarily wide wells with radii of 3.5 and 16.2nm under low-field and high-field conditions, respectively. It was concluded that the shape of the H5 potential well changed with increasing electric field.

F.D.Auret, S.A.Goodman, W.E.Meyer: Semiconductor Science and Technology, 1995, 10[10], 1376-81