Optothermal Raman measurement determined thermal conductivity characteristics in NiMn₂O₄ films grown by chemical solution deposition

Abstract

NiMn2O4 (NMO) thin films with different thicknesses (0.47–1.90 μm) were grown on Yttria-stabilized zirconia (YSZ)(100) substrates by chemical solution deposition (CSD). The effects of different growth conditions on the structural and thermal properties of NMO films were investigated. X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements show that both the average grain size of the samples and the surface roughness become larger with an increase of thickness. Based on isothermal surface condition, the corresponding thermal conductivity of NMO films was extracted from the optothermal Raman measurement and the obtained thermal conductivity is ∼4.0 ± 0.8 W m−1 K−1 for micrometer-scale films, suggesting that the (grain) boundary phonon scattering plays a minor role to affect the thermal conductivity of thin NMO films.

Revealing Low Thermal Conductivity of Germanium Tin Semiconductor at Room Temperature

“…Another approach presented [50] was to ensure that the film's thickness was higher than the laser diameter to remove the thermal effect imposed by the substrate, which thus, limits such measurements from thinner film materials. Although, a theoretical model and numerical solution [7,36,37] were presented to address these difficulties in thermal conductivity measurement of thin film material via Raman spectroscopy by thermally isolating the effect of the substrate from the film material, however, the behavior of such substrate acting as a heat sink to the film material on top was not considered as could be evidenced in a typical model of heat transfer in any multi-layer material (Figure 6).…”

“…In this work, first, a reliable microfabrication approach to isolate the film from either the thermal effect or strain of the buffer layer or substrate was presented. Second, the measurement model for a radial Gaussian distribution as contained in the textbook on conduction of heat in solids [35,36] was utilized in the calculation of thermal conductivity. Thermometric measurement which was responsible for the temperature-dependent vibration mode for sample surface temperature was made from relaxed bulk Ge 1−x Sn x /Ge/Si epilayers via the in situ micro-Raman spectroscopy at 633 nm excitation laser wavelength at a non-heating power density.…”

“…Our analysis is based on the radial Gaussian heat distribution model. [35][36][37] Thermal conductivity for each sample, at 5 and 9% Sn content, was calculated using measurements of the sample's surface temperature, ΔT = Δ𝜔/𝜂, obtained from temperature dependency of Ge-Ge mode shift, seen in Figure 2b. Local temperature was measured at the surface of the sample by applying the heating laser power density to cause peak shift, ignoring any wide peak shifts associated with overheating.…”

Application of Synchrotron Radiation-Based Fourier-Transform Infrared Microspectroscopy for Thermal Imaging of Polymer Thin Films

“…A common approach to obtain thermal maps or local temperatures of a sample is based on Raman spectroscopy. Optothermal Raman or Raman thermometry is one of the most popular and widely used techniques for characterizing the temperature of two-dimensional materials [ 16 ], thin films [ 17 , 18 ], substrates [ 6 , 19 , 20 ], and suspended semiconductors [ 20 , 21 , 22 , 23 , 24 , 25 ]. Using Raman thermometry, the local temperature can be measured in four different ways: (i) through the ratio of the Stokes and anti-Stokes signal amplitudes and calculation of the temperature based on a Boltzmann distribution of the ground and first excited state populations [ 26 ]; (ii) via the analysis of the band position; (iii) linewidth; and (iv) intensity of a Raman mode followed by a determination of the temperature dependence of the associated spectral characteristic [ 6 ].…”

Measurement of Thermal Conductivity of Suspended and Supported Single-Layer WS2 Using Micro-photoluminescence Spectroscopy

“…At present, the methods for measuring the thermal conductivity include the steady-state method, time-domain thermal reflection (TDTR), 3ω methods, optothermal Raman method, and so on. Among them, TDTR is one of the most commonly used noncontact methods for measuring the (interfacial) thermal conductivity of bulk material and thin films .…”