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Measurement of electron beam heating technique. (a) Sketch of electron beam heating technique. ∆T L and ∆T R is temperature rise in left and right Pt thermometer, separately. R(x) is the cumulative thermal resistance along the suspended nanowire from the left thermometer to the scanning point of x. The yellow pyramid denotes the irradiating electron beam. (b) Length-dependent cumulative thermal resistance of different nanowires, which are #4, #6, #8, #11, #13 and #14. The slope of amorphous regions overlaps with each other, even for different nanowires with different amorphous lengths, meaning that the amorphous regions with various lengths keep constant thermal conductivity around 1.9 ± 0.25 W/m·K. The cumulative thermal resistance of the rest silicon nanowires is shown in Supporting Information Fig. S5.
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While numerous studies have been carried out to characterize heat transport behaviours in various crystalline silicon nanostructures, the corresponding characteristics of amorphous one-dimension system have not been well understood. In this study, we amorphize crystalline silicon by means of helium-ion irradiation, enabling the formation of a compl...
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... as the final irradiation dose, sufficient to amorphize the silicon without introducing significant roughness at the crystalline/amorphous interface (CAI) and most importantly, without causing any appearance of voids. Using this approach, we created amorphous segments of varying lengths in 15 such nanowires, as shown in Supporting Information Fig. S2. To ensure that every silicon atom has equal probability of being impinged by a helium ion, the ion beam scan step size is kept to ~0.25 nm, smaller than the lattice spacing of silicon, considering the growth direction along the [111] direction for the silicon nanowires used in this study. Figure 1(a) shows a short amorphous region ...
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... conductance along the nanowires with amorphous segments was measured using an electron beam heating technique that we had previously developed, with details discussed elsewhere 27,[34][35][36] . The measured Silicon nanowires with diameter ~160 nm were purchased from Sigma-Aldrich 730866) with a [111] growth direction. As shown in the sketch in Fig. 2(a), a SEM electron beam is used to heat up the suspended nanowire on a Micro-Electro-Thermal System (METS) device and the temperature rise at two ends of nanowire is probed by the two platinum (Pt) loops (thermometers). ∆T L and ∆T R denote the temperature rise in the left and right Pt thermometers, respectively. At a thermal steady ...
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... thermal resistance of six silicon nanowires measured across the amorphous segments is presented in Fig. 2(b), for Samples #4, #6, #8, #11, #13 and #14. Although silicon nanowires have different amorphous region lengths (L) on different METS devices, the thermal resistance curves of the (unirradiated) crystalline parts of the silicon nanowires are either overlapping or parallel to each other, implying the same thermal conductivity, which is ...
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... segment, and this linear relationship is observed for all the measured samples. Similarly, we calculate the thermal conductivity of the amorphous silicon segments using the formula κ = 1/(dR(x)/dx)/A, which is around 1.7 ± 0.1 W/m·K, and is the same as that obtained by a linear fit of the cumulative thermal resistance obtained previously in Fig. 2(b). The consistency of the value of thermal conductivity obtained by these two approaches doubly confirms the repeatability in extracting the final thermal conductivity. For the amorphous silicon nanowires studied in this work, the contribution of propagons to thermal conductivity is negligible considering the diameter filtering effect ...
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... regions with different lengths. The linear dependence of cumulative thermal resistance on amorphous region lengths is shown and the thermal conductivity of amorphous silicon can be obtained by linearly fitting the curve, which is 1.7 ± 0.1 W/m·K, similar to that obtained from linearly fitting the cumulative thermal resistance previously in Fig. 2(b). www.nature.com/scientificreports www.nature.com/scientificreports/ Fig. 4(b), which is defined as R INT = 1/h INT . Our measured ITR between amorphous and crystalline silicon shows same order of magnitude in value to that predicated by theoretical calculation 38 ...
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