Wannier-Stark and quantum confined Stark effects are demonstrated in GaInAs/InP and GaInAsP/InP quantum well structures grown by gas source molecular beam epitaxy. The structures are characterized by photoluminescence and photocurrent spectroscopy. The analysis of the absorption edge of wells of different sizes shows that wide GaInAsP wells are preferable for the realization of QCSE absorption modulators at 1.55-mu-m. A blue shift of 16 meV under an electric field of 20 kV/cm has been observed in a GaInAs/InP Wannier-Stark structure.