Measurement of interface defects in gated SIMOX structures

Defects in gated or ungated thin film resistors have been characterized by photoinduced transient spectroscopy (PITS). These resistors were fabricated with n- or p-type SIMOX (separation by implanted oxygen) wafers implanted with 200-keV oxygen to 1.8×10 ¹⁸ cm^-2 total fluence. PITS data confirm a defect density dependence upon the thermal treatment used to fabricate SIMOX wafers. More residual damage is observed in resistors fabricated with a wafer annealed at 1275°C than in resistors fabricated with a wafer annealed at 1325°C. The applied gate field, perpendicular to the film resistor and its interfaces, controls persistent photoconductive effects, thus confirming the macroscopic barrier model in SIMOX, which was proposed by H.J. Queisser (1985) for gallium arsenide film structures. The PITS data indicate that electron or hole traps in SIMOX are located at the conductive-film-buried-silica interface