Electron beam defined surface gratings in AlGaAs with precisely controlled duty cycle using a multiple line exposure technique

We describe the fabrication of surface gratings in AlGaAs with precise control of duty cycle using a multiple line electron beam exposure technique. Using the electron beam resist as an etch mask for the subsequent chemically assisted ion beam etching, we have fabricated near ideal rectangular gratings with a periodicity of 290 nm and a duty cycle ranging from 34% to 73%. The duty cycle is conveniently controlled by utilizing the linear dependence of the duty cycle on the line spacing during the electron beam exposure.