Si3N4 film was adopted as a barrier layer for SiO2 aerogel/GaAs system. Si3N4/GaAs formed an almost chemically sharp interface and nearly maintained their chemical inertness during in-situ heating until 400 degreesC under ultra high vacuum condition. One micrometer thick SiO2 aerogel film was prepared on the Si3N4/GaAs system using supercritical drying procedure at 250 degreesC and under 1160 psi. The thickness of Si3N4 barrier layer was varied as 400, 600 and 900 Angstrom. The dielectric constant of all SiO2 aerogel/Si3N4/GaAs system was measured as approximately 1.9 and almost no difference was observed from the changes in the thickness of Si3N4 barrier layer. The leakage current densities were measured as low as under 2 X 10(-7) A/cm(2) and these values are two orders smaller than that of SiO2 aerogel/GaAs system prepared without the introduction of Si3N4 barrier layer. All the aerogel/Si3N4/GaAs systems show ohmic conduction at low applying field and space charge limited conduction at high applying field. Furthermore, a reduced leakage current behavior was observed with increased Si3N4 layer thickness and could be explained from the electric-field depression effect due to accumulated charges in the films. (C) 2003 Elsevier B.V. All rights reserved.