Direct wafer bonding is a viable technique for fabricating high-voltage devices. An understanding of the microstructure and electrical behavior of the bonded interface is critical for device fabrication. In this paper, we investigated the microstructure of the silicon-to-silicon bonded interface using cross-sectional transmission electron microscopy and the corresponding electrical behavior using spreading resistance probing. Results indicate that oxide precipitates were present at the bonded interface when Czochralski silicon wafer were used in the process. Oxide precipitates were noticeably absent from the bonded interface when float zone wafers were bonded to each other. We find that oxide precipitates at the interface arise not due to the residual oxide at the surface prior to wafer bonding but due to gettering of oxygen from the Czochralski wafer. Spreading resistance measurements show occurrence of a high resistivity region at the bonding interface whether or not oxide precipitates are present.