Reduction in interface state density of SiO2/Si-IPL/InP by fluorine and sulfur passivations

Abstract

The characteristics of a liquid-phase-deposited SiO2 film on InP were investigated. The mixture of H2SiF6 and H3BO3 aqueous precursors was used as the growth solution. SiO2 on InP with (NH4)2S treatment showed good electrical characteristics owing to the reduction of native oxides and sulfur passivation. The electrical characteristics were further improved with an ultrathin Si interface passivation layer (IPL) through reductions in Fermi-level pinning and interface state density. Moreover, during the SiO2 deposition, the HF in the growth solution simultaneously and effectively removed native oxides from the Si-IPL and provided fluorine passivation on it. The Al/SiO2/Si-IPL/(NH4)2S-treated InP MOS capacitor showed superior electrical properties. The leakage current density reached 6.9 × 10−9 and 1.6 × 10−7 A/cm2 at ±2 V. The interface state density reached 3.6 × 1011 cm−2 eV−1 with low frequency dispersion of 12.3%.