Structures, compositions, and optical properties of ZnCr2O4 films grown epitaxially on c-sapphire by pulsed laser deposition

•ZnCr2O4(1 1 1) films were epitaxially grown on c-sapphire substrates by PLD for the first time.•The in-plane orientation relationship was revealed to be ZnCr2O4 [0 1 −1]||Al2O3 [1 −1 0].•(2 2 2) rocking-curve half-width and surface RMS roughness are as small as 0.07° and 0.585 nm.•The Zn/Cr atomic ratio increases linearly from 0.316 to 0.585 upon increasing oxygen pressure from 0.1 to 7 Pa.•ZnCr2O4 films bandgap can be modulated from 3.61 to 3.87 eV by increasing the oxygen pressure.