Influence of shadow effect on the growth and shape of InAs nanowires

The influence of shadow effect originating from the neighboring nanowires on the nanowire growth is theoretically investigated. The nanowire axial and radial growth rates and the nanowire shape are shown to be strongly dependent on the nanowire surface density and the direction of incident flux. Theoretical predictions are compared with the experimental shapes of InAs nanowires grown by the Au-catalyzed molecular beam epitaxy. In particular, the barrel-like shape observed in dense arrays of InAs nanowires is well described by the model. Very importantly, we show that the shadow effect helps to avoid otherwise enabled radial growth and to preserve the cylindrical nanowire shape.