BEHAVIOR OF GALLIUM ON VICINAL SI(100) SURFACES

The behavior of sub-monolayer coverages of Ga on vicinal Si (100) surfaces has been studied by scanning tunneling microscopy-Substrates were cut at 4° towards the (Oil) direction, resulting in a near-single-domain surface with double-height steps spaced an average of 39 Å (≈ 10 unit cells) apart. At room temperature, low coverages of deposited Ga do not disrupt the Si surface. The Ga atoms appear to lie on the existing Si dimers, appearing as bright features in the STM images. However, if the sample is annealed after Ga deposition, there is significant disruption of the step structure. At low coverages (<0.1 monolayer) the degree of disorder along the step edges appears to correlate with the amount of Ga on the surface. The double-height steps become kinked, or split into single height steps. Up to 0.1 monolayer no clear evidence of Ga growth on top of the Si dimers is observed, either at step edges or on the flat terraces. Rows and arrays of Ga are seen at higher coverages. Comparison of these results with earlier work on untilted Si (100) shows that Ga is more reactive at double-height steps than at single-height steps. © 1990, American Vacuum Society. All rights reserved.