Modeling of A-DLTS spectra of MOS structures

Abstract

Acquisition of basic characteristic of defects has become possible through a wide class of measurement techniques which probe the interface, the near interface, as well as the bulk of semiconductor. Results presented here are based essentially on the acoustic version of Deep Level Transient Spectroscopy (A-DLTS) measurements. This method is based on the acoustoelectric response effect observed at the interface. The A-DLTS uses the acoustoelectric response signal (ARS) produced by MOS structure interface when a longitudal acoustic wave propagates through a structure. The ARS is extremely sensitive to external conditions of the structure and reflects any changes in the charge distribution connected with charged traps. The temperature dependence of ARS after bias voltage step application is investigated and the activation energies and some other parameters of traps at the insulator – semiconductor interface are determined. The results obtained form Arrhenius plots of A-DLTS spectra of selected MOS structures are compared with results obtained from modeling of ADLTS spectra using theoretical model.