Epitaxial ScAlN Etch-Stop Layers Grown by Molecular Beam Epitaxy for Selective Etching of AlN and GaN

This is the authors' abstract. We don't add key points for this paper.

Although selective dry etches exist for GaN, it is difficult to selectively etch AlN in heterostructures with other conventional III-N epitaxial materials. The reduction in etch rate resulting from the addition of 2%-16% scandium to Sc x Al 1-x N in conventional Cl 2 /BCl 3 /Ar inductively coupled plasma etching is presented. Smooth, epitaxial Sc x Al 1-x N layers are grown by RF-plasma-assisted molecular beam epitaxy directly on 4H-SiC substrates. The etch selectivity with respect to AlN is as high as 10.6 and 11.2 for x = 0.02 and 0.16, respectively, allowing Sc x Al 1-x N to act as an etch-stop layer with minimal misfit strain when grown within either AlN or GaN based heterostructures.