Throughout history, the development of new materials has been the driving force for technological change. The past few decades are remarkable in that materials can now be designed and fabricated with atomic precision.

A number of new microscopy methods provide beautiful pictures of atoms on surfaces; such pictures have become routine covers photos for journals. Among the limitations of microscopy techniques is that the samples must be constant and unmoving during the observation, and often the images are limited to the top-most surface of an object. High-energy X-ray techniques can overcome these limitations; they interact very weakly with a material and they have can penetrate through chemically reactive atmospheres.

For instance, to further understand the growth of semiconductor materials, CHESS Staff Scientist R. Headrick has organized a consortium of Cornell scientists who use X-rays to monitor the growth of materials in real-time. A common procedure to grow semiconductor materials is CVD, or chemical vapor deposition, during which ions from a gas vapor settle onto a crystal surface and wander until they stick at a favorable site. In this manner, crystals of very high quality and purity grow in a layer-by-layer fashion. X-rays play an important role in that they easily penetrate through the atmosphere of reactive gasses, and the reflected X-rays count the number of the atomic layers and the quality of the crystalline films.

The Cornell group has used X-rays to characterize surface mobility, nucleation and growth. These studies have helped refine the methods used to grow a new semiconducting material: Gallium-Nitride. Gallium-Nitride is an unusual wide-bandgap semiconducting material that can be used to make diodes and lasers that emit blue light. Having a much shorter wavelength than common red diodes, the blue diode is expected to have an enormous technological impact. For example, in the area of information storage, the optical storage of the well-known CD-ROM will grow by a factor of ten due to being able to read and write smaller bits of information.