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

Abstract

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 μ m at 1335 K, 1⩽l⩽10 μ m at 1480 and 1560 K). Confrontation of the experimental data with the expression for the step rate (when l≪ λ s) ν=2 abKτ s( R− R e)( l/ Kτ s)/(2+( l/2 λ s) 2+ l/ Kτ s) (derived in the BCF model) provides a ground to conclude that the condition l/ Kτ s≪1 is fulfilled in our experiments (here R and R e are the deposition rate and its equilibrium value, the product ab is the atomic area, K is the step kinetic coefficient, λ s is the mean diffusion distance and τ s is the life time of an adatom). In other words, our results provide a ground to estimate the characteristic length d= D s/ K by rewriting l/ Kτ s≪1 in the form D s/ K≪ λ s 2/ l. In our experiments the interstep distance l reaches a value l=10 μ m and λ s 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 μ m, i.e., d=D s /K≪100 μ m.