Site control of Ga droplet array on CaF2 by surface modification using a focused electron beam

Site-controlled Ga droplet formation on CaF2 film by means of focused electron beam exposure was applied to the fabrication of a two-dimensional ordered nanostructure array. The proximity effect of this method was investigated as a function of the period of the dot array and the electron dose per dot site. A two-dimensional Ga droplet array, in which the diameter of each droplet was approximately 20 nm, with a 100 nm period was obtained. The minimum period which can control the formation site was found to be related to the exposed region at the As/CaF2 interface, and may be reduced by improving the process conditions such as by using a small beam spot and a thinner As film.