Elimination of interface defects in mismatched epilayers by a reduction in growth area

We have eliminated interface defects from the mismatched In0.05Ga0.95As/ (001)GaAs interface by controlling the size of the growth area. 2-μm-high pillars with different lateral shapes and dimensions were defined within the GaAs substrate before the molecular beam epitaxial growth of 3500 Å of In0.05Ga0.95As, greater than four times the critical thickness. On the pillars, the linear density of misfit dislocations was reduced from >5000 dislocations/cm for large (several hundred μm lateral dimensions) growth areas to nearly zero for 25 μm lateral dimensions. The dislocation density remains less than 800 dislocations/cm for lateral dimensions up to 100 μm. We find that there is also a decrease in dislocation density in narrow channels between the pillars; therefore, the pillars also block the glide of misfit dislocations.