FABRICATION OF SIGE QUANTUM DOTS ON A SI(100) SURFACE

This paper reports a method to produce SiGe quantum dots on a Si(100) surface, which is based on the selective adsorption effect of hydride molecules on a partially hydrogen-terminated Si(100) surface. It is sh own that etching of Si(100) surfaces for a limited time in ammonium fl uoride (NH4F) solution initially produces an atomically flat and dihyd ride-terminated surface and that further etching leads to the formatio n of microscopic (111) facets which are regularly distributed along th e surface. Hydrogen atoms are found to desorb completely from dihydrid e sites at similar to 400 degrees C while those from monohydrides rema in stable up to 650 degrees C. Hence, we show that in the temperature range of 400-650 degrees C, SiGe growth occurs only on the sites that were previously terminated by dihydrides, i.e., free of hydrogen. We d emonstrate that SiGe dots formed by using this approach are much small er in size (similar to 400 Angstrom) and more uniform than dots formed by the strain-induced growth mode transition.