Atomistic simulation of phonon and alloy limited hole mobility in Si1–xGex nanowires



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The role of alloy and phonon scattering is theoretically explored in 5 nm diameter SiGe nanowires at room temperature. Low-field mobility calculations are performed by utilizing sp3d5ds*-spin–orbit-coupled tight binding model for electronic structure and Boltzmann transport formalism. Three different transport orientations 〈100〉, 〈110〉 and 〈111〉 are considered. Alloy scattering is found to play an important role in these Si1–xGex nanowires, leading to a characteristic ‘U’ shaped mobility curve as a function of alloy composition. It is concluded that to extract any advantage of higher Ge hole mobility by alloying, Ge% > 70% is needed. Furthermore, the 〈111〉 channel orientation exhibits the highest hole mobility while 〈100〉 has the lowest hole mobility for any given alloy composition. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)