Research lights the path to superior electro-optical performance of aluminum scandium nitride alloys

From integrated photonics to quantum information science, the ability to control light with an electric field (a phenomenon known as electro-optic effects) supports critical applications such as light modulation and frequency conversion. These components rely on nonlinear optical materials that can manipulate light waves by applying electric fields.

Conventional nonlinear optical materials such as Niobate lithium have a large electro-optical response, but are difficult to integrate with silicon devices. In searches for silicon-compatible materials, the aluminum scandimium nitride (ALSCN), which was already flagged as a good piezoelectric, is the ability of the material to generate electricity when pressure is applied, or when an electric field is applied. It refers to the ability to transform. Come to the front. However, better control and means of properties to enhance the electro-optic coefficients are still needed.

Researchers at Chris Van De Walle’s Computational Materials Group at UC Santa Barbara have clarified how to achieve these goals. Their research published in Applied Physics Letters explain how to improve performance by adjusting the atomic structure and composition of materials. Although a large amount of scandium is required for a strong electro-optic reaction, the specific arrangement of scandium atoms within the ALN crystal lattice is important.

“We have found that by using cutting-edge atomistic modeling, placing scandium atoms in a normal array along a specific crystal axis significantly improves electro-optic performance,” says Ph.D. , Haochen Wang explained. Students who led the calculations.

This finding prompted researchers to investigate what is called superlattice structure. In the so-called superlattice structure, an alternating atomicly thin layers of SCN and ALN are deposited. This is an approach that can be implemented experimentally using sophisticated growth techniques. They found that precisely oriented layer structures actually provide a significant enhancement of electro-optic properties.

Interestingly, scientists also realized that strain could be exploited to adjust properties close to the “Goldilocks” point where the greatest electro-optic enhancement is obtained. Strain can be caused by externally applied stress. Alternatively, it can be incorporated into the material through carefully designed microstructures. This is a daily approach in silicon technology. Careful strain tuning can result in electro-optic effects in ALSCN. This is a digit that is much larger than the current material, niobet lithium.

“We are excited by the possibility that ALSCN will push the boundaries of nonlinear optics,” Van de Wall said. “Equally important, the insights excluded from this study allow us to systematically investigate other so-called heterostructure alloys that could further improve performance.”