Highly sensitive thermal conductivity measurements of suspended membranes (SiN and diamond) using a 3ω-Völklein method

Abstract

A suspended system for measuring the thermal properties of membranes is presented. The sensitive thermal measurement is based on the 3ω dynamic method coupled to a Völklein geometry. The device obtained using micro-machining processes allows the measurement of the in-plane thermal conductivity of a membrane with a sensitivity of less than 10nW/K (+/-5×10 −3 Wm −1 K −1 at room temperature) and a very high resolution (∆K/K = 10 −3 ). A transducer (heater/thermometer) centered on the membrane is used to create an oscillation of the heat flux and to measure the temperature oscillation at the third harmonic using a Wheatstone bridge set-up. Power as low as 0.1nanoWatt has been measured at room temperature. The method has been applied to measure thermal properties of low stress silicon nitride and polycrystalline diamond membranes with thickness ranging from 100 nm to 400 nm. The thermal conductivity measured on the polycrystalline diamond membrane support a significant grain size effect on the thermal transport.

Heat transport by long mean free path vibrations in amorphous silicon nitride near room temperature

“…2, even after removing the sample from the cryostat and remeasuring many weeks later (see Supplemental Material). Figure 3 compares the thermal conductivity of Si-N determined from five measurements of our suspended Si-N bridges [LP1 (hollow circles), LP2 (hollow triangles), and LP3 (solid circles)] with previously reported measurements for amorphous Si-N films grown using LPCVD [35][36][37] and plasma-enhanced CVD (PECVD) 38 , as well as to vitreous silica (SiO 2 )…”

Growth Monitoring With Submonolayer Sensitivity Via Real-Time Thermal-Conductance Measurements

“…The high coincidence between both datasets suggests that the behaviour of the sensor is purely driven by heat transport physics. This is an important difference from the device presented by Sikora et al 20 , where the use of a NbN strip sensor allowed measurements at very low temperatures, but produced non-negligible electrical effects due to the high electrical impedance of that material. Finally, as shown in Fig.3c, the uncertainty of the conductance measurement has been determined at two different current intensities, 300 A and 500 A, which generated temperature amplitudes of about 2 K and 6 K and produced a standard deviation of data equal to 8 nW/K and 1.3 nW/K respectively.…”

“…A remarkable contribution to the field was achieved by Völklein et al in 1990 who developed a suspended membrane-based sensor using a long and thin Pt electrical transductor operated in DC to measure in-plane thermal conductivity of thin films 15 . More recently, Sikora et al went a step further in improving this technology by combining the Völklein geometry with the AC 3 -method, reaching exceptional thermal conductance sensitivity, Δ ≅ 10 −320, 21 .…”

Quantum Phonon Transport in Nanomaterials: Combining Atomistic with Non-Equilibrium Green’s Function Techniques

“…Moreover, while considerable progress has been achieved in nanoelectronics in the implementation of local electrodes and gates over very short length scales, establishing temperature gradients over nanoscopic length scales remains a considerable challenge. In this respect, for characterizing thermal devices, novel sophisticated experimental techniques have been developed, such as the 3 method [ 20 ] and the frequency domain thermoeflectance [ 21 ], pioneered by Cahill et al [ 22 ]. This has led, in turn, to the modification of atomic force microscopes for thermometry [ 17 , 23 ] and to the development of Scanning Thermal Microscopy [ 18 , 24 ].…”