We investigated the electronic properties of epitaxially stabilized perovskite SrIrO3 and demonstrated the effective strain-control on its electronic structure. Comprehensive transport measurements showed that the strong spin-orbit coupling renders a novel semimetallic phase for the J_eff=1/2 electrons rather than an ordinary correlated metal, elucidating the nontrivial mechanism underlying the dimensionality-controlled metal-insulator transition in iridates. The electron-hole symmetry of this correlated semimetal was found to exhibit drastic variation when subject to bi-axial strain. Under compressive strain, substantial electron-hole asymmetry is observed in contrast to the tensile side, where the electron and hole effective masses are comparable, illustrating the susceptivity of the J_eff=1/2 to structural distortion. Tensile strain also shrinks the Fermi surface, indicative of an increasing degree of correlation which is consistent with optical measurements. These results pave a pathway to investigate and manipulate the electronic states in spin-orbit-coupled correlated oxides, and lay the foundation for constructing 5d transition metal heterostructures.
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