A regular array and method of forming a substantially regular array of microscopic
structures on a surface of a sample is described. A device of the present invention
comprises a microscopic layer of at least one first material on a substrate of
a second material, wherein the microscopic layer is sufficiently thin that stress
fields at the interface of the microscopic layer and the substrate cause formation
of separated regions of the first material on the substrate. The microscopic layer
on the sample is irradiated by means of a particle beam at an acute angle to influence
the direction of alignment of the separated regions and/or the relative position
of adjacent the separated regions.