This article reports the quality of InxGa1−xAs (0<x<0.2) layers grown on 15°-off GaAs substrate by metalorganic chemical vapor deposition. The crystalline quality of the InxGa1−xAs epilayers is determined by x-ray reciprocal space mapping (RSM). From the RSM results, the crystalline quality of InxGa1−xAs epilayers grown with small indium composition (x<0.11) is better than that of large indium composition (x>0.11) due to the small strain relaxation. The crystalline quality of InxGa1−xAs epilayer is found to strongly depend on indium content. The photovoltaic performance of p–n structure In0.16Ga0.84As solar cell shows the lower device performance, because the InxGa1−xAs films grown on 15°-off GaAs substrate show a large strain relaxation in the active layer of solar cell. It results in dislocation defects created at the initial active layer/InxGa1−xAs graded layer interface. The performance of In0.16Ga0.84As solar cell with p–n structure can be significantly improved by the p–i–n structure.