Cyclotron effective mass of holes in strained Si_1-xGe_x/Si quantum well structures

A far-infrared magneto-optical study of cyclotron effective mass of quasi-two-dimensional holes in strained Si1-xGex/Si quantum wells has been carried out on a series of samples with different Ge compositions at low temperatures and high magnetic fields up to 23 T. The in-plane effective mass determined from cyclotron resonance energies decreases systematically from 0.40m0 to 0.29m0 as the Ge composition increases from x = 0.13 to x = 0.37. The reduced in-plane mass and its variation with Ge composition are in good qualitative agreement with the strain effects on the valence band structure. © 1994.