Researchers from the University of Hamburg in Germany have fabricated large periodic arrays of AlGaAs semiconductor microdiscs using laser-interference lithography, reactive-ion etching and selective wet-chemical etching of GaAs with a citric-acid-based solution. Traditionally, microdiscs have been produced by electron-beam or optical lithography with an HF-based etching solution. High-resolution scanning electron microscope images revealed the high structural quality of the arrays. As reported in the July 22 issue of Applied Physics Letters, the researchers used temperature-dependent photoluminescence spectroscopy to verify that the optical quality of the microsdiscs was comparable to that of existing arrays. Controlling the parameters in the lithography process allowed them to switch from dotlike to antidotlike photoresist patterns, producing microdiscs that are coupled in one or two lateral directions.