BOEMDET-Band Offsets and Effective Mass Determination Technique utilizing Fowler-Nordheim tunneling slope constants in MIS devices on silicon

Abstract

The Fowler-Nordheim carrier tunneling slope constants for electron and hole conduction through MOS devices fabricated on silicon substrate are utilized to determine the conduction and valence band offsets, carrier effective masses in the SiO2 and its unknown bandgap, independent of photoemission spectroscopic measurements of band offsets on SiO2/Si samples. The slope constants are obtained from the electron and hole tunneling currents versus voltage characteristics on a pair of n-MOS and p-MOS devices in accumulation or an n-channel MOSFET device in inversion that allows carrier separation. This characterization technique called BOEMDET, can be applied to other insulating materials grown or deposited on silicon, such as JVD nitride, HfSiON, SiOxNy, and high-K oxides found viable for future MOS technology. To an accuracy of one decimal place, the conduction band offset for the SiO2/Si MIS structure is determined to be 3.2 eV, the valence band offset obtained is 4.6 eV and the bandgap of SiO2 is found to be 8.9 eV. The electron and hole effective masses in the SiO2 are calculated to be 0.42m and 0.58m, where m is the free electron mass. In case of quantum confinement at the SiO2/Si interface, the electron and hole masses correct to 0.51m and 0.65m. Also, the carrier effective masses in thermal SiO2 are found to be the same for all thickness of the oxide. Keywords: effective mass, FN-tunneling, band offsets, metal-insulator-semiconductor