Band structure of strained Si/(111)Si 1- x Ge x : a first principles investigation

Abstract

There has been a lot of interest in the strained Si CMOS technology lately,especially the modification of band structures which provides a theoretical basis for the design of the high-speed and high-performance devices and circuits.Calculations were performed on the band structures in(001)-biaxially strained Si on relaxed Si1-XGeX alloy with Ge fraction ranging from X=0 to 0.4 in steps of 0.1 by CASTEP approach.It was found that both the conduction band(CB)and valence band(VB)edge degeneracies are partially lifted due to strain,that electron effective mass is unaltered under strain while the hole mass along [100] direction decreases obviously with increasing X,and that the fitted dependences of CB,VB splitting energy and indirect bandgap on X are all linear.The results can supply valuable references to the investigation in the Si-based strained MOS devices enhancement and the conduction channel design related to stress and orientation.