Validity of the parabolic effective mass approximation in silicon and germanium n-MOSFETs with different crystal orientations

J.P.J. van der Steen, David Esseni, Pierpalo Palestri, Luca Selmi, Raymond Josephus Engelbart Hueting

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    Abstract

    This paper investigates the validity of the parabolic effective mass approximation (EMA), which is almost universally used to describe the size and bias-induced quantization in n-MOSFETs. In particular, we compare the EMA results with a full-band quantization approach based on the linear combination of bulk bands (LCBB) and study the most relevant quantities for the modeling of the mobility and of the on-current of the devices, namely, the minima of the 2-D subbands, the transport masses, and the electron density of states. Our study deals with both silicon and germanium n-MOSFETs with different crystal orientations and shows that, in most cases, the validity of the EMA is quite satisfactory. The LCBB approach is then used to calculate the values of the effective masses that help improve the EMA accuracy. There are crystal orientations, however, where the 2-D energy dispersion obtained by the LCBB method exhibits features that are difficult to reproduce with the EMA model.
    Original languageUndefined
    Article number10.1109/TED.2007.900417
    Pages (from-to)1843-1851
    Number of pages9
    JournalIEEE transactions on electron devices
    Volume54
    Issue numberLNCS4549/8
    DOIs
    Publication statusPublished - 1 Aug 2007

    Keywords

    • EWI-10797
    • IR-61859
    • METIS-241797
    • SC-DPM: Device Physics and Modeling

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