Step flow growth of vicinal (1 1 1)Si surface at high temperatures: step kinetics or surface diffusion control

We used a novel technique for reflection electron microscopy observation of Si surfaces during crystal growth to determine how the rate ν of step motion depends on the interstep distance l. Our measurements manifest a linear dependence of ν on l in a wide interval of values of the interstep distance (0.2⩽l⩽8 μm at 1335 K, 1⩽l⩽10 μm at 1480 and 1560 K). Confrontation of the experimental data with the expression for the step rate (when l≪λs) ν=2abKτs(R−Re)(l/Kτs)/(2+(l/2λs)2+l/Kτs) (derived in the BCF model) provides a ground to conclude that the condition l/Kτs≪1 is fulfilled in our experiments (here R and Re are the deposition rate and its equilibrium value, the product ab is the atomic area, K is the step kinetic coefficient, λs is the mean diffusion distance and τs is the life time of an adatom). In other words, our results provide a ground to estimate the characteristic length d=Ds/K by rewriting l/Kτs≪1 in the form Ds/K≪λs2/l. In our experiments the interstep distance l reaches a value l=10 μm and λs is definitely larger (that is why we observe ν∼l), so that a reasonable value of the right-hand side of this inequality is 100 μm, i.e., d=Ds/K≪100 μm.