Single crystalline substrates for III-V growth via exfoliation of bulk single crystals

To enable widespread deployment of GaAs PV, the cost of single crystal substrates must be dramatically reduced. Here we present an indium-bonded exfoliation technique that produces substrates for III-V growth by exfoliation of macroscopic single crystals. Beginning with a search of available substrates, we identified several model materials that are lattice matched to III-Vs. Bi2Se3 single crystals were grown via the Bridgman technique in order to demonstrate our exfoliation method. From a centimeter diameter single crystal, up to eleven substrates with RMS roughness of 0.04 nm in a 20x20 micron region were exfoliated using this method. Large area AFM scans determined a terrace length of 72 mu m between step edges. Thicknesses were determined to range from 40-160 mu m using cross-sectional SEM. This exfoliation technique opens the door to the widespread study of layered materials as epitaxial substrates.