Electron beam-enhanced etching of InAs in Cl2 gas and novel in situ patterning of GaAs with an InAs mask layer

Abstract

We propose and demonstrate a novel in situ patterning process of GaAs and GaAs/AlGaAs heterostructures in which a thin InAs layer is used as an electron-beam resist layer for Cl2 gas etching in ultrahigh vacuum environment. It has been found that the etch rate of InAs by Cl2 gas is far lower (by a factor of 500) than that of GaAs but this etch rate can be enhanced by electron beam irradiation by a factor of 20, allowing the pattern formation in the InAs mask layer. By delineating a stripe pattern in the InAs resist and subsequently etching in situ the GaAs underneath, we have successfully formed a fine V groove. Since this process is clean and damage free, it is suited for the fabrication of quantum structures in which high-quality etch/regrowth interfaces are required.