THE ELIMINATION OF SURFACE CROSS-HATCH FROM RELAXED, LIMITED-AREA SI1-XGEX BUFFER LAYERS

The influence of lateral dimensions on the relaxation and surface topo graphy of linearly graded Si1-xGex buffer layers has been investigated . A dramatic change in the relaxation mechanism has been observed for depositions on Si mesa pillars of lateral dimensions 10 mu m and below . Misfit dislocations are able to extend unhindered and terminate at t he edges of the growth zone, yielding a surface free of cross-hatch. F or lateral dimensions in excess of 10 mu m orthogonal misfit interacti ons occur and relaxation is dominated by the modified Frank-Read (MFR) mechanism. The stress fields associated with the MFR dislocation pile -ups result in a pronounced cross-hatch topography. (C) 1997 American Institute of Physics. [S0003-6951(97)04443-4].