We report results of the photoluminescence, photoluminescence excitation, and magneto-photoluminescence spectra measurements performed on modulation doped ZnSe/BeTe/ZnSe type-Ⅱ quantum well structures at low temperature (2—5 K). The non-doped sample showed two distinct peaks, while the doped one showed one peak only. The linear polarization degree measured in both photoluminescence and the photoluminescence excitation spectroscopy indicates that photoluminescence transitions of an indirect type takes place at respective heterointerfaces. The peak splitting in the non-doped sample was caused by a built-in electric field resulting from the spatial separation of charges along the growth axis. We found optical Shubinkov-de Hass oscillations in both the photoluminescence intensity and the transition energy under a high magnetic field perpendicular to the well. These features and the additional absorption (or reflection) spectra measurements demonstrated that two-dimensional electron gas of a high concentration was formed in the doped samples. All these present the signature of charged excitons and also of a correlated excitonic phase of type-Ⅱ quantum wells.