Profile and groove-depth control in GaAs diffraction gratings fabricated by preferential chemical etching in H2SO4-H2O2-H2O system

We studied in detail the fabrication of diffraction gratings in GaAs by preferential chemical etching and demonstrated that different grating profiles can be obtained by proper choice of substrate orientation and direction of grating-mask groove openings or by controlling the width of these groove openings and/or etching time. We have also obtained experimental curves relating the etched groove depth to etching time for gratings with different periodicities at different etchant temperatures. In our experiments, the H2SO4-H2O2-H2O system was used as the preferential etchant together with Shipley AZ-1350J as the resist. This combination enables us to use the resist grating directly as a protective mask during chemical etching.