Site-controlled growth of GaAs nanoislands on pre-patterned silicon substrates

Abstract

GaAs islands have been grown by molecular beam epitaxy on Si (100) substrates patterned with nanoscale holes using only few monolayer deposition thicknesses. The site-controlled growth has been achieved without masking the Si surface with SiO2 between the patterned holes. The nucleation density of GaAs islands between the patterned holes shows a strong dependence on the growth temperature, V/III beam flux ratio and nominal deposition thickness. Through the selection of optimal growth parameters GaAs islands have been grown highly selectively in the patterned holes over a wide range of hole diameters for fixed spacing as well as over a wide range of spacings for fixed diameter of the holes. The influence of pattern features (hole diameter, spacing) on the morphological properties of the site-controlled GaAs islands has been investigated in detail. A (5 × 5) μm2 AFM image of GaAs nanoislands selectively grown in patterned holes with 70 nm diameter and a spacing of 0.5 μm on Si substrate.