An evaluation of phase-shift analysis of modulated photocurrents

Abstract

The accuracy and limitations of phase-shift analysis of modulated photocurrents as a means of determining the energy profile of localized states in amorphous semiconductors have been investigated. The basis of the existing ‘recursion procedure’ is reviewed and its deficiencies are revealed by applying the method to computer-generated phase-shift spectra for model trap systems. Realistic conditions which can produce severe distortions in the trap profiles reconstructed in this way have been identified and examined. We propose a new method, based on the same experiment, which is equally simple in application and avoids most of the deficiencies inherent in the recursive method. The new method is demonstrated for both computer-generated data and preliminary experimental data on samples of arsenic triselenide.