The present invention describes a semiconductor interferometric reflecting device capable of modulating the reflected light by modulating the carrier concentration inside a semiconductor device. The variation of the carrier concentration within the device causes the variation of the physical optical properties inside the semiconductor material leading to a shift of the reflected and absorbed light spectrums. The modulating layer is fabricated on an optically smooth substrate, i.e., sufficiently smooth to allow for the occurrence of interference effects. Furthermore, if desired, the same device can be designed to emit or reflect the desired light. The present invention may be utilized for a reflective flat panel display comprising an array of semiconductor interferometric reflecting devices.