Optical saturation of room-temperature excitonic absorption in CdZnTe/ZnTe multiple quantum wells

Abstract

A well-defined room temperature excitonic absorption peak is a crucial property in photonic device applications of semiconductor multiple quantum wells (MQWs). Although II-VI semiconductor MQWs are potentially promising materials, especially in the bluer part of the visible spectrum, no room temperature excitonic absorption peak has been reported in these structures until recently. We present strong and well-defined room temperature n = 1, heavy-hole excitonic absorption peaks in CdZnTe/ZnTe MQWs. The temperature dependence of the excitonic absorption linewidth reveals that the homogeneous broadening, which is due to the excitonphonon interaction, is significantly smaller than that reported in a similar II-VI MQW system.1 The cw room temperature saturation intensity of the excitonic absorption peak was measured and found to be one order-of-magnitude higher than that reported in III-V MQWs. The high saturation intensity is a consequence of a smaller exciton Bohr radius, which is characteristic of wide-gap II-VI semiconductors. A high saturation intensity and well-defined room temperature excitonic absorption peak should be favorable for high power operation of electroabsorptive modulators and self electro-optic effect devices (SEEDs).