LEAPS-MPS: Nanopatterning Nitride Based Nanostructures Using Sequential Infiltration Synthesis for Optoelectronic Applications

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Non-Technical Summary:

Optoelectronic devices, including photodetectors, solar cells, and light-emitting diodes (LEDs), are essentially energy conversion devices which converts light to electricity or vice versa. These devices are used in many aspects of modern life such as telecommunication, energy, consumer electronics, and solid-state lighting. Most commonly the active material in optoelectronic devices are Gallium Nitride (GaN) or Aluminum Nitride (AlN).

These materials have attracted significant attention and are of great interest because of their emission in ultraviolet (UV) and visible wavelengths. Nanostructures of nitride materials are not as common as planar structures which are currently used in commercial devices, but they could enable future devices with novel functionalities. With this award from the LEAPS-MPS program researchers at Illinois State University develop nanopatterns of AlN and GaN by using a synthesis approach called Sequential Infiltration Synthesis (SIS).

SIS allows them to investigate the growth mechanism of the nitride materials as well as optical properties of nanostructures with different shapes morphologies. In addition to this research being of great interest to the semiconductor industry, the project also enhances the undergraduate education at a primarily undergraduate institution because students can participate in cutting-edge experimental research, which provides hands-on synthesis and characterization opportunities.

This effort also broadens the semiconductor workforce by integrating research results into the physics curriculum as part of an upper-level experimental physics courses. The recipient of this award, an early career female faculty member is a role model for female and minority students, encouraging them to choose STEM careers.

Technical Summary:

In the field of optoelectronic research, group III nitrides such as AlN and GaN have gained significant attention over last few decades due to their stabilities and as a wide band gap semiconductor with emission in the ultraviolet and visible ranges. The planar structured nitride materials currently used in commercial devices come with limitations such as defects and dislocations due to lattice mismatch with available substrates which consequently limit the performance of the resulting devices, high temperature requirements limiting choice of substrates and the dimensions are not suitable for futuristic nanoscale devices.

For emerging devices, the concerns related to planar structures can be alleviated by employing nanostructures of these materials. However, fabrication methods of nanostructured nitride materials are still in infancy and current approaches are complex and multi-step processes. Significant improvements and a fundamental understanding are needed regarding the growth of nitride nanostructures and subsequent long-range patterning of these nanostructures.

With this award from the LEAPS-MPS program the researchers synthesize AlN and GaN nanorod patterns using nanostructured block copolymer (BCP) templates and an inorganic deposition method called Sequential Infiltration Synthesis (SIS). The SIS process involves infiltration of gas phase molecules into soft polymeric materials. This project investigates the SIS growth mechanism for nitride materials using Fourier Transform Infrared Spectroscopy (FTIR) as well as other physical, structural and optical characterization techniques.

These and other methods, including scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), X-ray diffraction (XRD), photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy, and cathodoluminescence (CL) imaging, are used to study the resulting nanostructures. The proposed work opens up new avenues of research to realize nitride nanomaterial growth and patterning using SIS as a facile and cost-effective method.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.