Determination of electron and hole effective masses in thermal oxide utilizing an n-channel silicon MOSFET

Abstract

The gate tunnelling electron current and the substrate hole current obtained from carrier separation in an n-channel Si MOSFET are used to determine the parabolic electron and hole effective masses in the thermal oxide. The oxide voltages for electron and hole conduction in the n-MOSFET in inversion are formulated, and the carrier effective masses of 0.42m for electron and 0.58m for hole for a free Fermi gas model of carriers at the emitting electrode are determined using the Fowler-Nordheim tunnelling characteristics. These carrier masses are related to the band offsets in SiO2/Si MOS devices accurately through the MOSFET model for the first time. The carrier effective masses are predicted to be the same for all thickness of oxide. The technique can be extended to other insulating materials as well. Also, the 1/E model of the anode hole injection over the hole barrier of 4.6 eV completely explains the oxide breakdown in thin oxides of 5 to 10nm at high electric fields, and having a slope constant of 516 MV/cm.