ESR Centers and Charge Defects Near the Silicon/Silicon Dioxide Interface.
Research and development technical rept.,
ARMY ELECTRONICS RESEARCH AND DEVELOPMENT COMMAND FORT MONMOUTH NJ ELECTRONICS TECHNOLOGY/DEVICES LAB
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The Nishi-B esr center has been examined as a function of thermal oxidation and annealing conditions in single-crystal silicon wafers. It was observed that B concentration was not correlated with fixed surface-state charge density Q, despite some similarities in their behavior. In freshly oxidized wafers, B typically ranges up to 200 per nm sq, and Q up to 50 per nm sq. The concentration of B is highly dependent on cooling rates concentration does not depend on oxide thickness and B may be observed even in native oxides. The g-value of the orientation-averaged B signal 2.0064 favors its assignment to trivalent Si in a silicon environment, as in crushed silicon 2.0055, rather than to the well-studied E centers 2.0008 found in various forms of damaged silicon dioxide. In our thermal oxides, E centers were unobservable, and thus cannot be the main source of Q, despite their nominal positive charge. Preliminary evidence shows a correlation of B with initial, unannealed fast interface states N, supporting the idea that trivalent Si is the origin of these states. Author
- Solid State Physics