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

Abstract

The characteristics of liquid-phase-deposited SiO2 film on GaAs were investigated. A mixture of H2SiF6 and H3BO3 aqueous precursors was used as the growth solution. SiO2 on GaAs with (NH4)2S 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 SiO2 deposition, HF in the growth solution can simultaneously and effectively remove native oxides on Si IPL and provide fluorine passivation on it. The Al/SiO2/Si IPL/(NH4)2S-treated GaAs MOS capacitor shows superior electrical properties. The leakage current densities can reach 7.4 × 10−9 and 6.83 × 10−8 A/cm2 at ±2 V. The interface state density can reach a 2.11 × 1011 cm−2 eV−1 with low frequency-dispersion of 8%.