On errors in thermal conductivity measurements of suspended and supported nanowires using micro-thermometer devices from low to high temperatures

摘要

For micro-thermometer devices developed for thermal conductivity measurements of nanowires, it is found using finite element analysis that radiation heat transfer can cause nonlinear temperature profiles in the long supporting beams of the thermometers when the sample stage temperature is considerably higher or lower than room temperature. Although the nonlinearity alone does not introduce errors in the measured thermal conductance, it can cause errors in the measured temperature coefficient of resistance of the thermometers and needs to be minimized with additional radiation shields. For a design where the sample is supported on a silicon dioxide bridge between two micro-thermometers, the numerical analysis reveals that a two-dimensional temperature distribution can cause a 25percent error in the sample thermal conductance obtained from a one-dimensional heat conduction analysis for a high-thermal-conductance thin film sample covering only the center part of the oxide bridge. This systematic error is reduced considerably for a low-thermal-conductance nanowire sample. However, care must be taken to ensure that the random uncertainties in the two measured thermal conductance values of the bridge with and without the nanowires are much smaller than the thermal conductance of the nanowires.