Microfabricated TEM sections of amorphous superlattices

Internal structure of layered amorphous superlattices was studied using transmission electron microscopy. Amorphous semiconductor superlattices were sectioned for TEM study using a microfabrication technique which yields sections with accurately controlled dimensions suitable for quantitative image analysis. Sections were created with a lithographic technique that utilizes a submonolayer of colloidal particles as an etching mask. Images of the sections reveal that amorphous superlattices can be grown without cumulative roughening. The absence of cumulative roughening allows layers to be grown flat and smooth to within 5 Å on a ∼100 Å lateral scale even after deposition of hundreds of layers. In highly localized regions unusual defect structures appear as bifurcations of individual layers.