ATOMIC-FORCE MICROSCOPY STUDY OF SELF-ORGANIZED GE ISLANDS GROWN ON SI(100) BY LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION

In this letter, we present an atomic-force-microscopy investigation of the Stranski-Krastanov growth of Ge on Si(100). Upon increasing the b ase width of the islands, two morphology transitions are found. The fi rst transition occurs at a base width of similar to 50-60 nm and marks the: evolution from few-monolayer-thick terraces to square-base pyram idal islands. In the second transition, which takes place when the bas e width exceeds similar to 300 nm, the island shape changes from squar e base pyramids to tetragonal truncated pyramids. Both transitions are brought about by the need for the system to minimize the elastic ener gy. (C) 1997 American Institute of Physics.