Characteristics of liquid phase deposited SiO₂ on (NH₄)₂S-treated GaAs with an ultrathin Si interface passivation layer

The characteristics of liquid-phase-deposited SiO 2 film on GaAs were investigated. A mixture of H 2 SiF 6 and H 3 BO 3 aqueous precursors was used as the growth solution. SiO 2 on GaAs with (NH 4 ) 2 S treatment shows good electrical characteristics owing to the reduction of native oxides and sulfur passivation. The electrical characteristics are further improved with an ultrathin Si interface passivation layer (Si IPL) from the reduction of Fermi-level pinning and interface state density. Moreover, during the SiO 2 deposition, HF in the growth solution can simultaneously and effectively remove native oxides on Si IPL and provide fluorine passivation on it. The Al/SiO 2 /Si IPL/(NH 4 ) 2 S-treated GaAs MOS capacitor shows superior electrical properties. The leakage current densities can reach 7.4 × 10 −9 and 6.83 × 10 −8 A/cm 2 at ±2 V. The interface state density can reach a 2.11 × 10 11 cm −2 eV −1 with low frequency-dispersion of 8%.