The Effect of Defects and Acoustic Impedance Mismatch on Heat Conduction SiGe Based Superlattices
CALIFORNIA UNIV BERKELEY DEPT OF MECHANICAL ENGINEERING
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The cross-plane thermal conductivity of four SiGe, SiSi0.4Ge0.6, and Si0.9Ge0.1Si0.1Ge0.9 superlattices was measured using the 3omega technique. All four superlattices were found to have thermal conductivity values between 1.8 and 3.5 Wm-K, which are below the values of typical SixGe1-x alloys. The growth quality of these superlattices was evaluated qualitatively through the use of x-ray diffraction and transmission electron microscopy. These studies indicated that the superlattices contained a relatively high density of defects. The low thermal conductivity values are presumed to be due in large part to these defects.