Analysis on thermal properties of tin doped indium oxide films by picosecond thermoreflectance measurement
Schematic diagram of rf sputtering system.
Schematic diagram of picosecond thermoreflectance measurement system. Full width of half maximum of pump and probe laser pulses are 2 ps and the pulse repetition rate is 76 MHz. The pump laser pulse line was modulated by acoustic optical modulator (AOM) by 1 MHz, which is described in upper part of this figure. Intensity of probe laser reflected by specimen surface was measured using photodiode and thermoreflectance signal was detected using lock-in amplifier.
Cross-sectional TEM images of Mo/ITO/Mo layered thin films deposited on fused silica substrate, where the thicknesses of the intermediate ITO layer are (a) 27 nm, (b) 46 nm, and (c) 62 nm, respectively.
X-ray diffraction patterns of ITO thin films.
Electrical properties of ITO films as functions of film thickness.
Thermoreflectance signals of the Mo/ITO/Mo three-layered thin films obtained by the picosecond thermoreflectance measurement.
Thermoreflectance signal of the Mo thin film of 69 nm in thickness obtained by the picosecond thermoreflectance measurement.
(a) One-dimensional heat diffusion model of a three-layered system by pulse heating, where and denote the film thickness and the thermal diffusivity, and subscripts of 1, 2 and 3 shows layer 1, layer 2, and layer 3, respectively. In addition, and represent the boundary thermal resistance between layer 1/layer 2 and layer 2/layer 3, respectively. (b) Schematic illustration of the temperature history curve at the rear surface of layer 3 opposite to the heated area, which has been standardized as the maximum temperature rise is 1. The areal heat diffusion time is defined as the area surrounded by the temperature history curve, and .
Total amount of thermal resistance for the Mo/ITO/Mo three-layered films, where the black bar shows the value of the thermal resistance for the respective layers and the white one shows the value of the boundary thermal resistance at Mo/ITO interface.
Thermophysical properties of molybdenum thin film obtained by picosecond thermoreflectance measurement.
Structure of specimens (see Fig. 3) and areal heat diffusion time obtained by picosecond thermoreflectance measurement along with thermophysical properties of Mo and , where , , and represent thermal diffusivity of Mo thin film, heat capacity per unit volume of Mo bulk (Ref. 24) and heat capacity per unit volume of bulk,24 respectively.
Thermophysical properties of ITO thin film, where , , and represent the thermal diffusivity of ITO thin film, thermal conductivity of ITO thin film, and boundary thermal resistance at the ITO/Mo interface, respectively. In addition, represents reported thermal conductivity (Ref. 25) of ITO target.
Thermal resistance and boundary thermal resistance for the three-layered films, where , , , and represent thermal resistance of Mo layer, thermal resistance of ITO layer, boundary thermal resistance at the ITO/Mo interface, and total thermal resistance of the three-layered films, respectively.
Electronic thermal conductivity for ITO thin films estimated from a Fermi gas model along with carrier density and Hall mobility .
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