Ability of capacitance–voltage transient technique to study spatial distribution and electric field dependence of emission properties of deep levels in semiconductors

In this work it is demonstrated conclusively that the capacitance-voltage transient technique can be used to analyse the spatial distribution and to study the electrically enhanced emission phenomena of deep levels in semiconductors. Results obtained using the technique for two types of defect, namely, the damage induced in silicon by boron implantation processes, and the DX centres in silicon doped AlGaAs alloys (the most commonly encountered defects in these materials) are presented. For the boron implanted silicon, the existence of two deep levels with non-homogeneous concentrations located in the lower half of the band gap was found. With regard to the DX centres, the experimental data show that these centres do not exhibit electrically enhanced emission rates, at least for the present experimental values of the electric field, in spite of the well established donor nature of these centers. This result can be explained in terms of the characteristic that these levels show thermally activated capture rates.