Band structures in orientation-controlled CuI thin films under epitaxial strain

Cuprous iodide (CuI) is a wide bandgap (\ensuremath{\sim}3.1 eV) semiconductor of great recent interest because its high transparency, hole conductivity, large exciton binding energy, and sizable spin-orbit interaction. However, studies on single-crystalline thin films have been scarcely reported. Here, we report the epitaxial growth CuI their optical characterization to elucidate modification band structure caused by anisotropic strain. Thin were grown molecular beam epitaxy nearly lattice-matched (only 0.1%-mismatched) InAs substrates with (001), (110), (111) crystal orientation, yielding pseudomorphic structures lattice coherence atomic-level flatness. Both reflectance photoluminescence spectra exhibit sharp profiles over temperature range. We assign transition energies deduce modifications associated strain varying orientation. Furthermore, determine deformation potentials which relate modification. The systematic effect for various substrate planes will pave way future optoelectronic application CuI-based heterostructures.