High-field current transport and charge trapping in buried oxide of SOI materials under high-field electron injection

Mechanisms of the charge transfer, the charge trapping, and the generation of positive charge during the high-field electron injection into buried oxide of silicon-on-insulator structures fabricated by different technologies are analyzed based on the data obtained from current-voltage, injection current-time, and capacitance-voltage characteristics together with SIMS data. Electron injection both from the Si film and the Si substrate is considered. The possibility of using the trap-assisted electron tunneling mechanisms to explain the high-field charge transfer through the buried oxides of UNIBOND and SIMOX SOI materials is considered. It is shown that considerable positive charge is accumulated near the buried oxide/substrate interface independently from the direction of the injection (from the film or from the silicon substrate) for UNIBOND and SIMOX SOI structures. Thermal stability of the charge trapped in the buried oxides is studied at temperatures ranging from 20 to 400° C. The theory is compared with the experimental data to find out the mechanisms of the generation of positive charge in UNIBOND and SIMOX buried oxides.