Exploring the border traps near the valence band in the SiO2 - SiC system using above-band-gap optical excitation

Abstract

Studying near-valence-band (EV) defects at the insulator–n-type 4H-SiC interface is challenging due to the low minority carrier concentration. Herein, we present a technique for characterizing the border traps near EV in an n-type 4H-SiC MOS capacitor by generating holes using above-band-gap optical excitation (OE). A rise in capacitance was observed under OE (due to hole capture by border traps), remaining stable long after the optical stimulus was removed, resulting in a persistent photocapacitance effect. We show the dynamics of the capture process and perform a quantification of the captured holes in samples with thermally grown oxide and different postoxidation annealing treatments. Published by the American Physical Society 2024