STEP-EDGE STRUCTURES ON SI(112) AND (113) SURFACES TREATED IN NH4F SOLUTION

Step edge structures on H-terminated Si (112) and (113) surfaces have been investigated with infrared absorption spectroscopy. NH4F acid is used to prepare almost straight bilayer step edges on the surfaces. It has been found that the step edges with the dihydride fluctuate withi n the width of one row of Si-H oscillators. The reason for the fluctua tion is attributed to the etching of Si atoms of straight step edges d uring NH4F treatment. The assignment of C mode absorption has been ref ined based on our experimental result. Therein, the surface orientatio n dependence of the absorption spectra is quantitatively investigated by taking account of the effect of step fluctuation. The ratio of actu ally fluctuating step edges to original step edges is estimated.