Impacts of orientation and cross-sectional shape on hole mobility of Si nanowire MOSFETs

We fabricated 〈100〉, 〈110〉, 〈111〉, and 〈112〉 p-channel gate-all-around Si nanowire (SiNW) MOSFETs, cross sections of which are rectangles with various widths, and investigated the hole mobility of the SiNW MOSFETs using the double Lm method. Measured hole mobilities of SiNW MOSFETs were about 80–140 cm²/Vs at surface carrier density of 1 × 10¹³ cm⁻². The dependences of the hole mobility on orientations and cross-sectional shapes of nanowires were analyzed. The orientation and geometry dependences can be explained by the band structures calculated by tight-binding approximation.