Ryan Hool Email & Phone Number

Champaign, Il, Us

Albuquerque, New Mexico, United States

Urbana-Champaign, Illinois Area

Lee group in Electrical & Computer Engineering DepartmentNASA Space Technology Research Fellow (Aug 2018 – July 2022)• Worked as a small team on and currently lead the project to improve our epitaxial III-V on Si tandem solar cells• Identified defects harming ~1.7 eV GaAsP top cell and improved epitaxial design to mitigate these defects enabling 1-sun AM1.5G efficiency up to 17.6% and 25.0% for GaAsP 1J and GaAsP/Si 2J devices, respectively• Investigated threading dislocation density (TDD) of GaP with varied doping on Si, reducing TDD nearly in half for p-type and undoped GaP and by more than an order of magnitude for n-type GaP• Studied ~1.7 eV GaAsP solar cells before and after electron irradiation showing n+/p junction polarity resulted in superior radiation hardness than p+/n• Co-led research group through three maintenance cycles to resource/repair molecular beam epitaxy (MBE) system for growth of III-AsP materials including two years as the primary leader• Troubleshot issues with substrate rotation/positioning equipment for MBE system, determined parts needed for rebuild, hired engineer, and shadowed engineer during rebuild.• Performed as a team to install two new dopant sources and upgrade two group III effusion cells on MBE system• Routinely characterize epitaxial layer structures with SEM, XRD, AFM, Nomarski imaging, PL spectroscopy, and Hall measurements• Improved group’s capabilities for electron beam-induced current imaging and defect selective etching techniques to accurately determine of TDD in III-V materials• Experienced in solar cell device testing using LIV (with AM1.5G and AM0), DIV, EQE, IQE, reflectance, and Suns-Voc measurements• Developed group’s capabilities for temperature-dependent solar cell device testing and investigated ~1.7 eV GaAsP solar cells with > 100°C above and below RT• Mentored two undergraduate students in experimental investigation of GaP TDD and in analysis challenges of data images and large data sets

Greater Minneapolis-St. Paul Area

Leighton Group in Chemical Engineering & Materials Science Department• Investigated n-type {111}-faceted pyrite (FeS2) single crystals including high temperature resistivity, annealing in sulfur-poor atmosphere, and surface topography diversity• Grew high purity pyrite single crystals by chemical vapor transport to study bulk and surface properties• Performed structural characterization to examine phase purity, crystalline orientation, and surface topography• Observed atomic-level roughness with (111) interplanar spacing for pyrite crystals with atomic force microscopy• Rebuilt probe for electrical measurements with temperature control of sample in vacuum

Gera, Michigan

• Performed quality control measurements to determine safety of wheat for food supply• Recorded and communicated results to plant manager and crop insurance personnel to identify proper storage locations of shipments and document farmers needing assistance• Received increased responsibility in overseeing testing labs and diagnosing lab equipment errors

Doctor Of Philosophy (Ph.D.), Materials Science & Engineering

Thesis topic: Metamorphic III-V on Si Multi-Junction Solar Cells

Bachelor Of Chemical Engineering (Bche), Chemical Engineering

Activities and Societies: Tau Beta Pi, AIChEHonors thesis topic: High Temperature Electrical Properties of FeS2 Pyrite Single Crystals.

Education record