Absorption of gas-phase atomic hydrogen by Si(100): Effect of surface atomic structures

The atomic-scale surface structural evolution of Si(100) exposed to gas-pha se thermal hydrogen atoms, H(g), has been investigated by scanning tunnelin g microscopy and temperature-programed desorption mass spectrometry. For th e substrate temperature (T-s) between 420 and 530 K, dihydride species in 3 x1:H domains were selectively etched upon extensive exposures to H(g). As a result, etch pits grew laterally along Si surface dimer rows. The presence of these pits correlates with the absorption of H(g) into the bulk of Si(1 00), confirming our earlier suggestion that atomic-scale surface roughening caused by etching is a prerequisite for H(g) absorption. (C) 2001 American Institute of Physics.