Glancing Angle Deposition (GLAD)

A glancing angle is the shallow angle between an incoming beam or flux and the surface it strikes – as opposed to the angle measured from the surface normal.

In deposition, working at a glancing angle means the substrate is heavily tilted so that arriving atoms hit the surface at a very oblique trajectory.

This oblique geometry is what makes GLAD fundamentally different from conventional thin film deposition.

When atoms arrive at an oblique angle, they condense on the substrate surface and spontaneously form small atomic nuclei. These nuclei then act as physical obstacles.

Because deposition is line-of-sight, incoming atoms cannot reach the shadowed regions behind existing nuclei – a phenomenon known as ballistic shadowing. This causes growth to concentrate on the tops of nuclei rather than between them, and the resulting columns tilt naturally towards the deposition source.

By actively adjusting the tilt angle and rotation of the substrate during deposition, the growing film effectively becomes its own mask. This gives precise real-time control over column direction and geometry.