A scanning tunneling microscopy study of the reaction of si(001)-(2 x 1) with nh₃

We have performed a study of a semiconductor surface chemical reaction at the atomic level using a scanning tunneling microscope (STM). The “topographic” structure and electronic density of states are measured before and after reacting Si (001)-(2 X 1) with NH3. While both clean and NH3-dosed surfaces exhibit a (2X 1) symmetry, STM images reveal changes in the spatial distribution of occupied electronic states which allow us to distinguish reacted and unreacted Si(001) dimers. Using tunneling spectroscopy, the occupied and unoccupied surface states of the clean and reacted surface are identified. The results are interpreted in terms of a Si (001) - (2 X 1) H monohydride resulting from dissociative adsorption of NH3. © 1988, American Vacuum Society. All rights reserved.