THERMAL EMISSION PROCESSES OF DX CENTERS IN ALXGA1-XAS-SI

The main techniques for the measurement of the emission activation ene rgy of deep levels, including single-shot capacitance techniques and a dmittance spectroscopy, are applied to DX centres in III-V alloys and the results obtained are discussed. The experimental data reveal that techniques based on voltage or capacitance transients provide higher v alues for the emission energy than those obtained by admittance techni ques. We explain these differences by considering the specific propert ies of these kinds of defects and the different approaches on which bo th types of experimental techniques are based. In addition, we have an alysed the effects of the electric field on the emission properties by using the capacitance-voltage transient technique (CVTT). Through an accurate study of the electric field evolution in the space charge reg ion of the junctions we conclude that no electric field enhancement of the electron emission rates is produced. This fact means that the Poo le-Frenkel effect does not take place or that, if it exists, it is sup pressed by the short range potential due to thermally activated captur e. Copyright (C) 1996 Elsevier Science Ltd