High-throughput heterodyne thermoreflectance: Application to thermal conductivity measurements of a Fe–Si–Ge thin film alloy library

Abstract

A High-Throughput Time-Domain ThermoReflectance (HT-TDTR) technique was developed to perform fast thermal conductivity measurements with minimum user actions required. This new setup is based on a heterodyne picosecond thermoreflectance system. The use of two different laser oscillators has been proven to reduce the acquisition time by two orders of magnitude and avoid the experimental artefacts usually induced by moving the elements present in TDTR systems. An amplitude modulation associated to a lock-in detection scheme is included to maintain a high sensitivity to thermal properties. We demonstrate the capabilities of the HT-TDTR setup to perform high-throughput thermal analysis by mapping thermal conductivity and interface resistances of a ternary thin film silicide library FexSiyGe100−x−y (20<x,y<80) deposited by wedge-type multi-layer method on a 100 mm diameter sapphire wafer offering more than 300 analysis areas of different ternary alloy compositions.

High Throughput Nanoimaging of Thermal Conductivity and Interfacial Thermal Conductance

“…High-Throughput Time-Domain ThermoReflectance (HT-TDTR) enables faster thermal properties mapping (≈20 s per point), but diffraction also limits its spatial resolution to micrometer scales. 13 Photothermal induced resonance (PTIR) 14−16 uses a cantilever of an atomic force microscope (AFM) to transduce the photothermal expansion of the sample due to the absorption of mid-IR nanosecond laser pulses. The fast sample expansion pushes the AFM probe into oscillations with amplitudes proportional to the local absorption coefficient, 17−20 enabling IR spectroscopy and mapping with ≈10 to 20 nm 16,21 sample expansion dynamics.…”

Tutorial: Time-domain thermoreflectance (TDTR) for thermal property characterization of bulk and thin film materials

“…Since the laser repetition rate is usually a fixed value and is much larger than the modulation frequency, frep >> fmod, the functionality of ASOPS in thermal measurements would be greatly compromised without modulation (note that many advanced TDTR configurations discussed in Section III are achieved through the variation of modulation frequency in the range 0.1-20 MHz). To overcome this problem, Dilhaire and co-workers 172,173 proposed a high-throughput time-domain thermoreflectance (HT-TDTR) technique that combines ASOPS with high-frequency modulation of the pump beam, enabling fast and accurate measurements of thermal properties. Figure 14(b) shows a schematic of the ASOPS-based TDTR system.…”

“…and the expressions of the in-phase and out-of-phase outputs of the lock-in amplifier are: 172 A small beat frequency of Δf=1 Hz is usually needed so that a time constant of 30 μs can be chosen for the lock-in amplifier to avoid signal aliasing. 173 An oscilloscope is then used to record the signal as a function of the scan time or lab time t. Since the lab time recorded by the oscilloscope has been stretched by a factor of fpump/Δf compared to the equivalent delay time d t (see Figure 14 superlattices with various thicknesses (15-50 nm) 174 and the high-speed thermal conductivity mapping for a Fe-Si-Ge thin film alloy. 173 Another important feature of ASOPS is that the probing rate can be many times slower than the pumping rate, with fpump = nfprobe + Δf, where n is an integer.…”

“…173 An oscilloscope is then used to record the signal as a function of the scan time or lab time t. Since the lab time recorded by the oscilloscope has been stretched by a factor of fpump/Δf compared to the equivalent delay time d t (see Figure 14 superlattices with various thicknesses (15-50 nm) 174 and the high-speed thermal conductivity mapping for a Fe-Si-Ge thin film alloy. 173 Another important feature of ASOPS is that the probing rate can be many times slower than the pumping rate, with fpump = nfprobe + Δf, where n is an integer. This enables sampling of ultrafast phenomena at a much slower acquisition rate.…”

Phase constitution of the noble metal thin-film complex solid solution system Ag-Ir-Pd-Pt-Ru in dependence of elemental compositions and annealing temperatures

“…Besides, it is a unique highlystable MPEA that could stand extreme high-temperature (up to 1,500 K) and high-pressure (up to 45 GPa) without phase transition. Another example is the recently reported equiatomic fcc-AgAuCuPdPt alloy which shows enhanced catalytic performance for CO 2 reduction reaction [23]. However, compared to the reports published from transition and refractory metal MPEAs, not much is known about the phase stability and structural formation of their noble metal counterparts.…”