Abstract
A simplified technique has been developed for fabricating ultrafine GaAs gratings, exploiting electron-beam lithography, SiCl4 reactive ion etching (RIE) and single-layer masking. A 50-nm-thick single PMMA (polymethylmethacrylate) layer, directly exposed and not postbaked, is used as the etching mask. Using this technique, ultrafine diffraction gratings (period 60, 80, 120 nm) with good profile have been successfully fabricated on GaAs substrates. It is expected that the present technique will be applicable to the fabrication of finer structures such as quantum wires and dots.