Zhao Research Group

GLAD produces columnar structures through the effect of shadowing during film growth, while substrate rotation controls the shape of the columns. In this technique, there are three basic parameters that determine the morphology of the columns: the incident angle, the growth rate, and the substrate rotational speed. By changing the angle of incidence, the columns can be sculptured into a C-shape, S-shape, and zigzag shape, while by changing the ratio of the deposition rate to the rotational rate (which is defined as the pitch), the column morphology can be varied between matchstick, helical, and vertical columns. Since GLAD is a physical vapor deposition technique, it has many advantages in terms of controlling the growth of nanostructured thin films: 1. It can form a nano-column array naturally. 2. The porosity of the film can be controlled by changing the incident angle. 3. There is almost no restriction on materials since the growth process is a thermal evaporation. 4. The shape and in-plane alignment of columns can be easily modified. 5. It has the advantage of self-alignment due to the shadowing effect. 6. It can also generate three-dimensional nanostructures. These advantages make the GLAD technique very promising for nanostructure fabrications.