Molecular beam epitaxial regrowth on in situ plasma-etched AlAs/AlGaAs heterostructures

Epitaxial regrowth by solid-source molecular beam epitaxy (MBE) on dry etched heterostructures possessing exposed AlAs surfaces is accomplished for the first time using a vacuum integrated processing. Samples composed of multilayers of AlAs and AlGaAs are patterned with a SiO2 mask and are anisotropically etched using a low damage electron cyclotron resonance (ECR) SiCl4 plasma process. Etched samples are transferred in ultrahigh vacuum between the ECR and MBE chambers to avoid atmospheric exposure before regrowth. Microstructural analysis of the overgrown layers by scanning and transmission electron microscopy indicates that epitaxial regrowth on both the etched field and vertical sidewalls is achieved. The regrown material is found to contain microtwin plates, but few dislocations, indicating the good quality of the overgrowth.