GaAs photovoltaics and optoelectronics using releasable multilayer epitaxial assemblies

Compound semiconductors like gallium arsenide (GaAs) provide advantages over silicon for many applications, owing to their direct bandgaps and high electron mobilities. Examples range from efficient photovoltaic devices(1,2) to radio-frequency electronics(3,4) and most forms of optoelectronics(5,6). However, growing large, high quality wafers of these materials, and intimately integrating them on silicon or amorphous substrates (such as glass or plastic) is expensive, which restricts their use. Here we describe materials and fabrication concepts that address many of these challenges, through the use of films of GaAs or AlGaAs grown in thick, multilayer epitaxial assemblies, then separated from each other and distributed on foreign substrates by printing. This method yields large quantities of high quality semiconductor material capable of device integration in large area formats, in a manner that also allows the wafer to be reused for additional growths. We demonstrate some capabilities of this approach with three different applications: GaAs-based metal semiconductor field effect transistors and logic gates on plates of glass, near-infrared imaging devices on wafers of silicon, and photovoltaic modules on sheets of plastic. These results illustrate the implementation of compound semiconductors such as GaAs in applications whose cost structures, formats, area coverages or modes of use are incompatible with conventional growth or integration strategies.We thank T. Banks, J. Soares and T. Spila for help using facilities at the Frederick Seitz MRL; D. Stevenson, S. Robinson and D. Sievers for help with photography, SEM and four point probe measurements, respectively; and A. Gray for guidance in calculating the cell conversion efficiency and the calibration of the solar simulator. J.Y. thanks D. Shir for help with optics simulation. This paper is based partly on work supported by a National Security Science and Engineering Faculty Fellowship (NIR cameras and MESFETs) and by the US Department of Energy, Division of Materials Sciences (DEFG02-91ER45439), through the Frederick Seitz MRL and Center for Microanalysis of Materials at the University of Illinois at Urbana-Champaign (materials, growth aspects) and the Division of Energy Efficiency and Renewable Energy (DE-FG36-08GO18021) (solar cells). We also acknowledge the Center for Nanoscale Chemical Electrical Mechanical Manufacturing Systems in the University of Illinois, which is funded by the National Science Foundation (DMI-0328162) (printing-based manufacturing) and separate funding from the National Research Foundation of Korea through a grant (K2070400000307A050000310, Global Research Laboratory Program) provided by the Korean Ministry of Education, Science and Technology. J. J. C. acknowledges support by the Center for Energy Nanoscience, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences (DE-SC0001013). J.Y. acknowledges support from a Beckman Institute postdoctoral fellowship. S. J. thanks the Korea Research Foundation for a postdoctoral fellowship (KRF-2008-357-D00134)