Study of molecular-beam epitaxy growth on patterned GaAs (1 0 0) substrates by masked indium ion implantation

Ordered In(Ga)As nanostructures on GaAs are emerging as an important new class of optoelectronic and electronic materials. In this work, patterned GaAs (1 0 0) substrates were fabricated by masked indium ion implantation and subsequent annealing under arsenic capping. Anodic aluminum oxide templates are used as masks for indium ion implantation on GaAs substrate. The masked indium ion implantation substrate is used as a strain pattern for the nucleation of three-dimensional In(Ga)As islands on the GaAs substrate. Molecular-beam epitaxy growth of self-assembled In(Ga)As/GaAs quantum dots on the patterned GaAs (1 0 0) substrates has been studied. By adjusting the growth conditions, surprising alignment and pronounced round coalescence of dots under specific condition are realized. An explanation for the role of patterned substrate in determining the shape of the nanostructure is proposed. Our approach provides a general yet versatile route towards the creation of a range of nanostructure materials.