Cross-plane thermal conductivity of self-assembled Ge quantum dot superlattices
نویسندگان
چکیده
The self-assembled quantum dot structure is an interesting topic for physical investigation of zero-dimensional system. Due to the low-dimensional confinement effect, the Ge-on-Si quantum dot structure is expected to demonstrate novel optoelectronic properties that can be applied to develop Sibased technology competitive with traditional optoelectronic materials such as III-V compounds. In addition, it is predicted that low-dimensional systems can have a thermoelectric figure of merit, Z, much larger than that of bulk material due to enhanced electron transport and reduced thermal conductivity. Studies of Z enhancement stimulated by this prediction have been carried out on several material systems. Progress to date in Si/Ge quantum well superlattice material system indicated that Z enhancement in both in-plane and cross-plane directions can be realized. Furthermore, due to its d-like density of states, quantum dot structures are believed to have better Z enhancement than quantum wells. This was initially verified using the PbTe superlattice system. For the SiGe quantum dot system, there have been several studies on the phonon spectrum on Ge dot superlattices, though limited work has been done on the thermal transport properties of the Ge quantum dots. In this paper, we report systematically the investigation of cross-plane thermal conductivity of Ge quantum dot superlattices.
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