Exploring the border traps near the valence band in the ${\mathrm{Si}O}_2$-$\mathrm{Si}C$ system using above-band-gap optical excitation

Studying near-valence-band ($E_V$) defects at the insulator–$n$-type $4H$-$\mathrm{Si}C$ interface is challenging due to the low minority carrier concentration. Herein, we present a technique for characterizing the border traps near $E_V$ in an $n$-type $4H$-$\mathrm{Si}C$ 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.