Fig. 2: Synergy of inhibitor pairs on retarding step propagation.
a Schematic of a spiral hillock on COM (100) surface. b Time-elapsed in situ AFM images showing spiral propagation of steps on (100) surface at a supersaturation of 2.4 with 7.8 μM GaA. Red curved lines outline the step edge of the spiral hillock, and white arrows mark the protrusions that are formed at step edges. c–e Decrease of step velocity, v, of layer advancement relative to that in the absence of inhibitors, v0, along (001) step plane (c), (021) step plane (d), and (12\(\bar{1}\)) step plane (e) with increasing concentrations of CA in inhibitor pairs at the displayed ratios. Error bars represent the standard deviation from an average of 15–25 measurements of v. Lines are guides for the eye. f–h, Isobolograms depicting the synergistic retardation of v by inhibitor pairs of GaA/CA (f), PGA/CA (g), and PrA/CA (h). Open symbols represent the concentrations of individual inhibitors that elicit a certain percentage of inhibition. Solid lines correspond to additive cooperativity between the paired inhibitors for a certain percentage of inhibition (10–70%). Solid symbols indicate the concentrations of the paired inhibitors that evoke the same inhibition. Leftward shifts of symbols from the respective solid lines suggest synergistic cooperativity.
