The world demand for, and consumption of, energy is dramatically increasing, with an increasing demand for renewable non-fossil based sources of electricity. As well, there is an ever growing demand for increased power and sophistication in the satellite systems orbiting our planet, driven by our increasing reliance on high speed communication and data links. The conversion of light from the sun into electrical energy, using photovoltaics, is one avenue that can be explored to meet these challenges both on the earth and in space. The mission of our research group is to accelerate scientific breakthroughs in the discovery of nanoscale materials and structures that will advance the frontier of the conversion of light to electricity. Our focus is new materials synthesis, device modeling and simulation, solar cell device fabrication and demonstrating proof-of-principle of devices that will deliver a major boost to the world’s pursuit of innovative and transformative energy conversion products. The vision of our lab is to elevate the vast, and essentially free, solar energy resource to a viable and sustainable alternative to fossil fuels, and at the same time provide higher density and longer life sources of power to the space power community. We will do this by developing new paradigms for photovoltaic conversion that enable use of highly efficient materials, at lower cost and in ways that have not yet been attempted.
Our team’s expertise lies in vapor phase epitaxy (VPE) of III-V photonic devices and nanostructures, bandgap engineering using epitaxial nanostructures, novel photovoltaic devices such as the intermediate band solar cell, photovoltaic characterization, simulation and testing. Funding for this work is provided through multiple state and federal agencies as well as collaboration with small and medium businesses. Our work leverages student, faculty and industrial collaborators with a truly interdisciplinary nature spanning physics, engineering, materials science and chemistry. In addition, we have strived to use our research program to further strengthen our student’s training as well as enhance RIT educational outreach and industrial collaboration. The results of our work are disseminated through both publication and collaboration with major photovoltaic and electronics manufacturers.
Current Research Directions
- Epitaxial Crystal Growth by Metalorganic Vapor Phase Epitaxy (MOVPE)
- Low cost approaches to high efficiency III-V epitaxy
- Low bandgap Sb-based materials for metamorphic multijunction solar cells
- Nano-structures (quantum wells/dots) for enhanced efficiency photovoltaic cells.
- Intermediate band effects in As, P and Sb based QD solar cells
- Growth of semiconductor nanostructures using vapor phase growth techniques
- Novel Approaches to Power Conversion (alphavoltaics, thin-film III-V solar cells)
- Light management and photonic light trapping applied to nanostructures solar cells
- National Science Foundation
- Department of Energy
- Air Force Research Laboratory
- Army Research Laboratory
- Office of Naval Research
- Microlink Devices, Inc.
Lab Facilities and Capabilities
The NanoPV laboratory is equipped with an extensive array of photovoltaic test and measurement equipment for analyzing solar cells and photovoltaic materials. This equipment is state of the art, which positions us to quickly take advantage of new technologies and produce rapid prototypes of novel devices. Dr. Hubbard’s NanoPV laboratories encompasses 3 separate spaces with a combined total of over 5,000 square feet of research space. The labs are equipped with everything that is needed to grow photovoltaic devices using raw precursors, fabricate these devices in a cleanroom environment and then perform both standard and advanced testing of the material and electrical properties. Some of the equipment contained in the NanoPV laboratories includes:
- Aixton 3×2” Close Coupled Showerhead (CCS) metalorganic vapor phase epitaxy (MOVPE) system. Growth of As, P and Sb based III-V materials.
- EpiTTCurve optical pyrometer system for real-time in-situ monitoring of temperature, strain and reflectivity during MOVPE growth of III-V materials
- TS Space Systems two-zone close match solar simulator for multi-junction solar cells. Class A match to both AM0 and AM1.5 spectrum, 300 mm uniform beam size.
- Sula Technologies Deep Level Transient Spectroscopy (DLTS). Trap parameters can be determined, including density, thermal cross section, energy level and spatial profile.
- JY Horiba MicoOS Photoluminescence mapping system with Si and InGaAs array detectors.
- Optronix Laboratories OL-750 spectroradiometeric measurement system provides spectral response measurements with low noise and high dynamic range below 106 A/W.
- Newport IQE-200 Automated EQE/IQE measurement system enables high resolution spatial mapping of the spectral response from the sample when coupled with the motorized x/y stage.
- Photoreflectance spectroscopy used to measure optical properties of new materials.
- Dark current and JSC/VOC measurements in an enclosed dark probe station.
- Agilent B1500 Semiconductor Parametric Analyzer
A full list of available facilities and equipment for the NanoPV laboratory can be found here.
About Dr. Seth Hubbard
Dr. Hubbard is currently an Associate Professor of Microsystem Engineering and Physics at the Rochester Institute of Technology as well as serving as Director of the NanoPower Research Laboratory. He also serves as Extended Faculty in Materials Science, Sustainability and Imaging Science. Dr. Hubbard currently leads a team of six graduate students and three postdoctoral fellows working on the epitaxial growth, fabrication and characterization of nanostructured solar photovoltaic devices. He has received over $5M in funded external research related to photovoltaic device development, has authored or co-authored over 70 journal and conference publications on electronic and photovoltaic devices and received an NSF CAREER Award as well as the RIT Trustee Scholarship Award. Prior to RIT, Dr. Hubbard was a National Research Council (NRC) Postdoctoral Research Associate at NASA Glenn Research Center. Dr. Hubbard also serves as an Editor of the IEEE Journal of Photovoltaics and is actively involved in the organization of the IEEE Photovoltaics Specialists Conference. He has been the advisor to 3 post-doctoral fellows, 3 PhD graduates and over 10 MS students. Dr Hubbard serves the undergraduate community by offering co-ops/ internships and support for student senior capstone projects.
Prof. Hubbard received his B.S. in Physics from Drexel University, his M.S. in Electrical Engineering and Applied Physics from Case Western Reserve University, and his Ph.D. in Electrical Engineering from The University of Michigan. His doctoral research under Prof. Dimitris Pavlidis consisted of studying the effects of materials properties and epitaxial device design on high power GaN and AlGaN heterojunction field effect transistors grown using vapor phase epitaxy.
More information on Dr. Hubbard’s projects and research team can be found here www.drsethhubbard.com.
- M.A. Slocum, D.V. Forbes, G. Miller, B.L. Snith, J.G.J. Adams and S. Hubbard, " Development of InAlAsSb growth by MOVPE," Journal of Crystal Growth, April 2017.
- B.L. Smith, Z.S. Bittner, S.D. Hellstrom, G.T. Nelson, M. A. Slocum, A.G. Norman, D.V. Forbes and S. M. Hubbard, " InAlAs photovoltaic cell design for high device efficiency, "Progress in Photovoltaics, vol. 25, pp 706-713, Apr 17, 2017, Cover Image.
- N. Balades, D. L. Sales, M. Herrera, F. J. Delgado, M. Gonzalez, K. Clark, P. Pinsunkajana, N. Hoven, S. Hubbard, S. Tomasulo, J. R. Walters, and S. I. Molina " Effect of annealing on the compositional modulation of InAlAsSb,"Applied Surface Science, vol. 395, pp 105-109, Feb 15, 2017.
- I. Subedi, M. A. Slocum, D. V. Forbes, S. M. Hubbard, and N. J. Podraza "Optical properties of InP from infrared to vacuum ultraviolet studied by spectroscopic ellipsometry,"Applied Surface Science, Jan 5, 2017.
- Y. Dai, S. J. Polly,S. Hellstrom, M. A. Slocum, Z. S. Bittner, D. V. Forbes, and S. M. Hubbard, " Effect of electric field on carrier escape mechanisms in quantum dot intermediate band solar cells," Journal of Applied Physics, vol. 121, 013101, 2017.
- S. J. Polly, C. G. Bailey, A. J. Grede, D. V. Forbes, and S. M. Hubbard, "Calculation of strain compensation thickness for III–V semiconductor quantum dot superlattices," Journal of Crystal Growth, vol. 454, pp. 64-70, 2016.