Understanding the improved performance of strained Si/Si1−xGex channel MOSFETs

We have studied in depth the performance of superficial strained Si/Si1−x Gex channel MOSFETs. To do so, we developed a two-dimensional drift-diffusion simulator including inversion layer quantization and low-field mobility curves obtained by means of a Monte Carlo simulator. We have reproduced experimental results. The dependences of the performance enhancement obtained in these devices on the germanium mole fraction, the drain–source and gate–source voltages are described in depth. At high-longitudinal electric fields the transconductance improvement is reduced due to the common value of the saturation velocity for all the different germanium mole fractions.