Fabrication of ultrafine gratings on GaAs by electron beam lithography and two-step wet chemical etching

Abstract

50 nm period gratings were produced on thick GaAs substrates by using electron beam lithography and two-step wet chemical etching. The size was very close to the theoretical limit of the electron beam lithography. For transferring such a fine grating onto GaAs, a two-step wet chemical etching method was developed, where a H2SO4-H2O2-H2O system is first used to roughly etch the oxygen and carbon-contaminated GaAs surface, followed by surface planarization with a Br-CH3OH system.