Synopsis: X rays scratch the surface

A new x-ray scattering technique successfully probes the elastic properties of thin semiconductor films.
Synopsis figure
Credit: J. Serrano et al., Phys. Rev. Lett. (2011)

X rays scatter relatively strongly in a solid or liquid, which makes them ideal for studying the structure of materials when only a small amount is available. But since x rays are typically a 1 kilo-electron-volt or more in energy, it’s hard to see the tiny energy shift in an x ray when it scatters from a lattice vibration (10100 milli-electron-volts) in a solid. X-ray techniques tend to therefore be “specialized,” with one method being better suited to, say, figuring out the crystal structure of microscopic samples, while another is chosen for studying excitations.

Now, a multinational team lead by Jorge Serrano at ICREA - Polytechnic University of Catalonia, Spain, was able to measure the spectrum of lattice vibrations in a 6-micron-thick sample of indium nitride. The group has combined two well-established techniques—surface scattering and inelastic scattering—to understand the elastic properties of thin semiconductor films. As it would be in a real device, the indium nitride was grown on a sapphire substrate with a gallium nitride buffer layer in between, but Serrano et al. controlled the x rays in their experiment so they only graze the surface, and not the substrate underneath. The team’s results, which are reported in Physical Review Letters, compare favorably with calculations of the elasticity of indium-nitride, a semiconductor that could prove useful for new types of solar cells. – Jessica Thomas


Features

More Features »

Announcements

More Announcements »

Subject Areas

Materials Science

Previous Synopsis

Atomic and Molecular Physics

Steps toward a new quantum fluid

Read More »

Next Synopsis

Related Articles

Viewpoint: Hydrogen Hides Surprises at High Pressure
Condensed Matter Physics

Viewpoint: Hydrogen Hides Surprises at High Pressure

Measurements of the melting curve of hydrogen at unprecedentedly high pressures call for a refinement of the theories describing the material. Read More »

Viewpoint: Porous Materials Exhibit Granular-Like Stress Chains
Materials Science

Viewpoint: Porous Materials Exhibit Granular-Like Stress Chains

Simulations of porous materials exhibit internal stress patterns like those in granular materials, despite the fact that these two systems are practically “negative images” of each other. Read More »

Synopsis: Crumpled Graphene
Graphene

Synopsis: Crumpled Graphene

The crumpling of graphene sheets explains a “soft spot” in the material’s mechanical response. Read More »

More Articles