Size, position and direction control on GaAs and InAs nanowhisker growth

The self-organized, position-controlled and parallel growth of GaAs and InAs nanowhiskers is successfully demonstrated by using a metal-organic chemical vapour deposition method. The growth takes place preferentially along the [111] As direction with the aid of the catalytic effect of Au nanodroplets, and not along [111] Ga or In directions. The diameter and length of the whisker can be controlled artificially down to 10 nm and to over 1 mu m, respectively. Doping and composition control of p- or n-type such as GaAs-InAs heterostructure formation are possible along the length direction of the whisker by changing the source gases. In order to control the growth position of the whisker, positioning of a Au nanodroplet is essential and realized by a Lithographic method. By choosing the [111]B direction to the substrate surface and normal to the patterned side edges, and by positioning the Au nanodroplet on the side wall, the positioned planar nanowhisker growth and bridging are successfully demonstrated. The growth mechanism of the nanowhiskers is revealed by the scanning and transmission electron microscope observations. Nanometer-size Au-alloy droplets play an important role in the growth of the whiskers. The whisker growth process is governed by the vapor-liquid-solid growth mechanism. (C) 1998 Academic Press.