The newly acquired AIXTRON SE metal organic vapor-phase epitaxy (MOVPE) system is a vital piece of semiconductor equipment that can produce crystalline III-V semiconductors, so named because they consist of elements from groups III and V of the periodic table of elements. Metal-organic and hydride molecules are broken down into the constituent elements that are then reorganized on the substrate surface as a thin crystalline film. These crystals have semiconducting properties, with a wide range of materials available from binary, ternary, or higher order combinations of the group III and V elements. The substrate can be other III-V materials, more conventional semiconductors like silicon, or other crystalline or noncrystalline materials, which gives a glimpse at the wide range of possible material combinations available using the MOVPE.
The MOVPE technique has led to many technological advancements in the last 25 years, due in part to its nanoscale control of semiconductor composition and thickness. Some of these advances include the lasers and photo-detectors that power the backbone of the Internet and other long-distance communication systems, many of the transistors used to send and receive signals in our mobile communication devices, high luminous efficiency LED light bulbs, high storage density optical systems such as Blu-ray and some of the highest power conversion efficiency solar cells used both terrestrially and in satellites. The III-V area of research continues to be ripe for scientific discovery and advancement. Some of these areas include study of new material systems for optical and electronic devices, miniature devices based on quantum dots and nanowires, as well as integration of III-V materials with low-cost silicon for both integrated photonics and the next- generation high-speed transistors.
“This tool is the first of its kind at RIT and represents a major equipment acquisition for the university,” said Seth Hubbard, the project lead and an RIT associate professor in physics and microsystems engineering. “It opens a lot of doors for my research and my colleagues at RIT who work in the areas of photonics, nanomaterials, and microsystems. This tool will allow RIT scientists to explore many new avenues of research that were not possible before.”
The equipment was acquired through funding from the National Science Foundation, New York State’s Empire State Development, the Office of Naval Research, RIT’s Kate Gleason College of Engineering, and RIT's Office of the Vice President for Research. The state-of-the-art tool, located in the engineering college’s Semiconductor and Microsystems Fabrication Laboratory, represents a major upgrade to the RIT cleanroom user facility. The MOVPE will be used by numerous multidisciplinary research teams including Hubbard’s team working in quantum dot structures and solar cells. Other teams will use this tool for integrating III-V materials with silicon for photonics; advancing tunneling field effect transistors for the next generation of information processors; expanding infrared detector technology to longer wavelengths for astronomy and military applications; and combining carbon nanotubes and solar technology for lightweight space applications.
“We are all asking the question, ‘What is next after silicon?’ As we approach the limit of what silicon can do toward increasing our computing power, one of the possibilities is integrating III-V materials with silicon to harness the power of photons for optical information processing,” said Hubbard.
“In fact, integration of III-V and silicon is a cross-cutting theme to many of our faculty members’ work. For example, in my research area, one of
the biggest expenses with III-V solar cells is the substrate itself,” Hubbard explained. “Over 50 percent of the solar cells cost is the substrate. By finding innovative methods for combining the III-V layers with alternative, low-cost substrates, we hope to effect a direct cost reduction in the solar cell, which is carried over into reduced cost of the electrical power generated.”
These new frontiers in material development and processes will benefit industrial research and development teams through more timely experiments, testing, and assessment as well as provide new educational avenues for RIT’s student-researchers.
“Students have been actively involved here at the university with III-V device processing, modeling, and testing,” said Hubbard. “However, due to our outsourcing of the materials growth, they were never able to deal directly with the MOVPE tool. We now have the ability to have students get involved at all levels of the device cycle, from the birth of the material in the MOVPE tool all the way to the packing of devices.”
Added Michael Slocum, an RIT researcher and recent graduate of the microsystems engineering Ph.D. program, “The MOVPE system will allow us to expand our research interests due to the increased process control capabilities of this reactor. As a recent graduate, I truly appreciate the hands-on exposure students will receive on the MOVPE, which will dramatically increase their ability to learn a technical and valuable skill set.”
Regional universities and industry will also have access to RIT researchers and the facilities. The MOVPE process is quite expensive when it’s outsourced, but its availability at RIT will allow other universities and small businesses to prototype device designs affordably in a research setting.
“Bringing together scientists and engineers from industry with RIT faculty and student-researchers will lead to innovation in various industries related to imaging, optics, and photonics,” said Ryne Raffaelle, RIT vice president of research and associate provost. “It has long been a dream of mine to have this enabling technology at the university and it’s gratifying to finally see this dream become reality.”