Anisotropy of Hole Effective Mass of Strained Si_(1-x)Ge_x (001)

There has been a lot of interest in the strained Si1-xGex technology lately,which has been widely adopted to enhance mobility. In this paper,the effective mass along arbitrarily k wavevector directions and the isotropic effective masses in strained Si1-xGex/(001)Si were obtained with the framework of K.P theory. It is found that the obvious change occurs in the [1-11],[001],[1-10],[-110] and [100] directional effective masses of first and second valence band in strained Si1-xGex/(001)Si and that the isotropic effective mass of the first valence band is close to the one of the second,so the traditional concept of heavy and light hole is meaningless. The effective mass plays a significant role in the mobility enhancement. The results can supply valuable references to the investigation in the Si-based strained pMOS devices enhancement and the conduction channel design related to stress and orientation.