EVALUATION OF THE INTERFACE STATE DENSITY FROM LIGHT-INDUCED EFFECTS ON I-U CHARACTERISTICS OF SCHOTTKY DIODES

The change of forward I-U characteristics of an Al/Si Schottky diode u pon illumination at low temperature is observed. The current decays ra pidly with time immediately after the illumination is switched off, fo llowed by a slow change or saturation which is bias dependent. Light i nduced effect (Staebler-Wronski effect) on the I-U dark curves allows us to determine the incremental dark capacitance C(dark) which is foun d to be equal to the interface capacitance at low forward voltages. Th e density of interface traps D(s) obtained from C(dark) and that evalu ated from the light induced effect on the dark conductivity for the di ode under investigation have approximately the same values. Both techn iques show the existence of a peak in the interface density around 0.4 7 eV below silicon mid-gap.