HEATING CURRENT INDUCED CONVERSION BETWEEN 2X1 AND 1X2 DOMAINS AT VICINAL (001) SI SURFACES - CAN IT BE EXPLAINED BY ELECTROMIGRATION OF SI ADATOMS

Besides randomly walking on the crystal surface the adatoms are assumed to have a drift velocity c=DsF/kT, where Dsis the surface diffusion coefficient and F is a force, related in some way to the specimen heating current. In the limiting case of narrow terraces (small interstep distance l) the major process on the whole surface is the surface transport, which results an absence of noticeable conversion of the domain structure when Fl/kT≈0.1. Making use of the agreement between this conclusion and the experimentally observed [H. Kahata and K. Yagi: Jpn. J. Appl. Phys. 28 (1989) L858] lack of conversion (under reversal of the current direction) at l≈40-80 nm and T=700°C, the force F is estimated to be in the range 10-14-10-13N. Experimental verification of the predicted stability of vicinal surfaces with l<80 nm when F has step-up direction and instability (decay to large terraces, separated by steps of multiple height) when F has step-down direction can be a crucial test of the hypothesis for an electromigration of Si adatoms. © 1990 IOP Publishing Ltd.