Selective formation of Ge nanostructures on Si(1 1 1) surface with patterned steps

We demonstrate the selective formation of Ge nanostructures on Si(1 1 1) surface with the aid of step-band networks. Step flow growth in the step-band region decreases the critical thickness for transition from 2D to 3D growth. Under the step flow growth, step bunching and faceting are enhanced and the step edge with concentrated strain becomes the nucleation site. The spatial arrangement of Ge islands can be controlled by changing the growth mode locally.