Electron Mobility in Highly Doped MOSFET´s with Standard and Nitrided Gate Oxide

In this paper we report mobility measurements on highly doped n-MOSFET´s with both a 12nm thick oxide nitrided in N2O ambient and a standard gate oxide of the same thickness. While mobility in standard devices are in good agreement with data already available in literature, the nitrided samples feature a remarkable mobility degradation. Besides, at 77K the high field region of the experimental curves does not follow any universal behavior. Both C-V and charge pumping measurements demonstrates that the density of interfacial states and trapping centers in the mid-gap region is well above 10¹¹ cm^¿2; therefore, it is likely that the mobility in nitrided samples is impaired by the interface quality and a higher trapping density.