Passivation of substrates with hydrogen to reduce the number of electron traps in the buffer layer at the contact of silicon with Ba_1-xSr_xTiO₃

The performance of FeRAM non-volatile cells including those on ferroelectric insulating layers requires full-scale development of the field effect at the semiconductor–dielectric interface. The recharging of electron traps concentrated in the buffer layer between the insulator and the wafer impedes the development of the field effect at the interface. A Si wafer has been hydrogen-saturated for suppressing the activity of electron traps in the buffer layer at the ferroelectric–silicon contact. The reference specimen has been another similar wafer not exposed to H₂. High-frequency C–V curves of the metal–dielectric–semiconductor structures with Ba_0.8Sr_0.2TiO₃ insulating layers deposited on both wafers have been measured. The capacities of the test specimens have proven to be low sensitive to hydrogen saturation of the wafers. This is accounted for by long-term heating of the silicon wafers at 500–600 °C during ferroelectric deposition. It has been proposed to implant large organic cations into the wafers in order to reduce the concentration of electron traps in the Ba_0.8Sr_0.2TiO₃–Si buffer layers. Those organic cations can be 2–phenylethyl ammonium iodide, 4-chlorophenylethyl ammonium iodide and 4-fluorophenylethyl ammonium iodide which showed good results at passivation of high-performance metal–halogenide perovskite solar cells.