SUPPRESSION OF SURFACE ROUGHENING ON STRAINED SI SIGE LAYERS BY LOWERING SURFACE STRESS/

Stress-induced surface roughening usually occurs in strained semicondu ctor layers, such as SiGe layers on Si substrates, which is technologi cally undesirable. We demonstrate that the roughening of a strained Si 0.34Ge0.66 layer is suppressed by depositing a thin Si layer (less tha n or equal to 1.5nm). This thin Si layer is not stressed on the SiGe l ayer, which is lattice-matched to the Si substrate. The thin Si layer lowers the surface stress of the strained heterostructure, thereby pre venting the surface roughening. The main advantage of this method is t hat the surface roughening can be suppressed by making only a minor ch ange in crystal growth procedure.