SOME COMPLICATIONS OF THE DLTS TECHNIQUE CAUSED BY NONEXPONENTIAL RELAXATION OF BARRIER CAPACITANCE

The results of numerical modelling of Schottky barrier DLTS spectra in the case of non-exponential relaxation of the barrier capacitance are presented. We consider the following factors capable of inducing non- exponential relaxation: comparable densities of deep and shallow elect ronic traps, a substantial electric field dependence of the carrier ca pture cross sections of deep electronic traps, and a non-uniform spati al distribution of electronic traps in a semiconductor. The effect of these on a DLTS Spectral band may manifest itself in the band broadeni ng mainly due to a shift of the high-temperature 'shoulder' to higher temperatures, in the appearance of dependences of the shape and positi on of the DLTS spectral band on the bias voltage applied to the barrie r structure, and/or in a non-monotonic character of the above dependen ces. Since this behaviour of the DLTs band does not follow from the co nventional DLTS technique models, the algorithms commonly used to dete rmine the deep trap recombination parameters face some complications. A number of suggestions on how to overcome the complications are made. The complex behaviour of the DLTs band predicted by calculations for the metal-n-GaP Schottky barriers is illustrated by experimental data.