The photoluminescence (PL) properties of In0.53Ga0.47As/GaAs0.5Sb0.5 type II multiple quantum well (MQW) structures, lattice-matched to InP substrates grown by molecular beam epitaxy (MBE), were studied. It was found that a tunneling-assisted type II emission at about 2.3 mu m showed a remarkable Si-doping dependence. The PL intensity of the type Il emission was found to decrease drastically when the Si-doping concentration exceeds 2 x 10(17) cm(-3), followed by a remarkable increase in the full width at half maximum (FWHM) of the PL spectrum. It became clear that the observed PL intensity decreased and the PL spectral broadening were related to Si activity into the GaAsSb layers.