Asymmetry in the charge injection of SIMOX interfaces

Abstract

Summary form only given. The charge transport in the synthesized buried oxide of a SIMOX (separation by implantation of oxygen) structure shows deviation from the ideal Fowler-Nordheim dependence. An observed asymmetry of the injecting layers associated with the top and bottom Si/SiO/sub 2/ interfaces is reported. This observation is compatible with optical measurements which reveal the presence of an intermediate layer (10-40-nm thick) at the interface between the buried oxide and the bulk silicon substrate. Sequential ramp I-V measurements show a large reservoir of positive charge trapping centers. Little is known about the spatial distribution of the centers and their dependence on the high-energy oxygen implantation parameters. The sequential ramping measurements demonstrate maximum charge storage capacity of the buried oxide. The electron injection from the cathode is enhanced at a relatively low average field, and the current levels are higher by several orders than those of thermal SiO/sub 2/. This observation is compatible with silicon-rich-SiO/sub 2/ injectors. The effective barrier heights are considerably lower than the thermal SiO/sub 2/ barrier height. Also observed is a difference in the effective barrier heights at the top and bottom Si/SiO/sub 2/ interfaces, which leads to asymmetry in charge injection.<>