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-volt age transient technique can be used to analyse the spatial distributio n and to study the electrically enhanced emission phenomena of deep le vels in semiconductors. Results obtained using the technique for two t ypes of defect, namely, the damage induced in silicon by boron implant ation processes, and the DX centres in silicon doped AlGaAs alloys (th e most commonly encountered defects in these materials) are presented. For the boron implanted silicon, the existence of two deep levels wit h non-homogeneous concentrations located in the lower half of the band gap was found. With regard to the DX centres, the experimental data s how that these centres do not exhibit electrically enhanced emission r ates, at least for the present experimental values of the electric fie ld, in spite of the well established donor nature of these centers. Th is result can be explained in terms of the characteristic that these l evels show thermally activated capture rates.