The measurement of thermal conductivities using the photothermal deflection method for thin films with varying thickness

Abstract

This study considers non-contact methods that obviate the causes of measurement error, such as thermal contact resistance and the unnecessary destruction of samples. Among the methods, the photothermal deflection method has been adopted and developed to measure the thermal conductivities of thin-film materials. To apply the developed method for thin films, bi-layered materials are manufactured by depositing the film on Corning 7740 glass plates. The study also investigates the optimal modulation frequency, as related to the thermal diffusion length of the sample, for measuring thermal conductivities of thin films.. Aluminum, TiO 2 , and Si 3 N 4 films with micro/nanometer thickness were selected as the objects for measurement; the thermal conductivities of these films were experimentally measured. Samples of thickness ranging from 1 ㎛ to 200 ㎚ were prepared to measure the variations in thermal conductivities with thickness. It was observed that the thermal conductivity in submicroscale films decreased as the thickness was reduced.

A practical method for simultaneous determination of Poisson’s ratio and Young’s modulus of elasticity of thin films

“…Thin films have found increasing applications in many advancing technologies [1][2][3][4][5][6]. To increase the reliability, lifespan and structural stability of functional thin films and thin film structures, a better characterization of mechanical properties such as Poisson's ratio and Young's modulus of elasticity, which play an important role in the mechanical performance of thin films, is often found to be necessary.…”

Determination of deposit thickness in natural gas cooler based on the measurements of gas cooling degree

“…4. The method is based on the basic formula defined by Fourier's Law for the conductive heat transfer through a planar plate (layer) under steady state conditions [4][5][6][7][8]:…”

“…This may be determined from Eq. (8). Assuming the operation of four fans to cool the gas, the output capacity of the air K 2 can be defined as follows:…”

Numerical study on visualization method for material distribution using photothermal effect

“…Further, Q i is described as a periodic heat source: (3) as a type of sine wave with a specific frequency to simulate the modulated pump beam [12,16,17]. Q i has a gaussian distribution in the x and y directions.…”

“…The heat flux and temperaturebalanced condition between air and the test sample were set. After the temperature fields for the three domains are calculated, the deflection angle of the probe beam can be calculated by integrating the gradient of the index of refraction with respect to the temperature in the front air region along the probe beam path parallel to the sample surface [12,16,17]:…”