A single fin or a pair of co-integrated n- and p-type single crystal electronic device fins are epitaxially grown from a substrate surface at a bottom of one or a pair of trenches formed between shallow trench isolation (STI) regions. The fin or fins are patterned and the STI regions are etched to form a height of the fin or fins extending above etched top surfaces of the STI regions. The fin heights may be at least 1.5 times their width. The exposed sidewall surfaces and a top surface of each fin is epitaxially clad with one or more conformal epitaxial materials to form device layers on the fin. Prior to growing the fins, a blanket buffer epitaxial material may be grown from the substrate surface; and the fins grown in STI trenches formed above the blanket layer. Such formation of fins reduces defects from material interface lattice mismatches.