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 L_m 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.