On the universality of inversion-layer mobility in n- and p-channel MOSFETs

The authors report studies on the inversion-layer mobility in n- and p-channel MOSFETs with 10/sup 15/ to 10 /sup 18/ cm/sup -3/ substrate impurity concentrations. The validity and limitations of the universal relationship between the inversion-layer mobility and the effective normal field (E/sub eff/) were examined. Differences have been found in E/sub eff/ dependence between electron and hole mobility. A marked deviation from the universal curve due to substrate impurity scattering has been observed at low carrier concentration. The results suggest that by adding a term for the surface roughness scattering and the deviation due to Coulomb scattering to the universal curves, a more accurate description of inversion-layer mobilities can be realized over a wide range of substrate impurity concentration. The mobility degradation caused by carrier injection also has been studied.<
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