an epitaxial plane 18 b as shown by the rough saw marks 76 with the epitaxial structures separated fig7 the remaining gaas substrate material 50 u2032 is removed and then the etch stops 52 and 54 each of the epitaxial structures 40 42 may then be processed as conventional imm inverted metamorphic devices and can be used as a typical solar cell as shown in fig8 the bi facial epitaxial growth specifically shown as inverted triple junction solar cells in fig5 8 on each side of the substrate 50 use lattice matched 1 9 ev ingap epitaxial layers 56 and 62 and lattice matched 142 ev gaas epitaxial layers 58 and 64 and u02dc 2 of lattice mismatched 1 ev ingaas epitaxial layers 60 and 66 although specific features of the invention are shown in some drawings and not in others this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention the words u201c including u201d u201c comprising u201d u201c having u201d and u201c with u201d as used herein are to be interpreted broadly and comprehensively and are not limited to any physical interconnection moreover any embodiments disclosed in the subject application are not to be taken as the only possible embodiments in addition any amendment presented during the prosecution of the patent application for this patent is not a disclaimer of any claim element presented in the application as filed.