Design of Micro-Arrayed Thin Film Thermocouples (TFTC)

2003 ◽  
Author(s):  
Jong-Jin Park ◽  
Minoru Taya
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Heat Conduction ◽  
Steady State ◽  
Aluminum Nitride ◽  
Silicon Wafer ◽  
Measured Data ◽  
Bulk Materials ◽  
Thin Aluminum ◽  
Thin Film Thermocouples

We designed the thin film thermocouples (TFTC) made by T-type (Copper-Constantan) thermocouple arrays in order to measure temperature distribution at higher spatial resolutions. This sensor consists of a few different layers; silicon wafer, thin aluminum nitride (AlN) layer, and thin film thermocouple layers. The thickness of the thin aluminum nitride (AlN) layer is 100nm and the layer is located between silicon wafer and thin film thermocouples to construct an electrical insulator and thermal conductor. T-type (Copper-Constantan) thermocouples are deposited on the aluminum nitride (AlN) layer over the silicon wafer and the copper thickness and constantan thickness are 50nm, repectively. The sensor area is 10mm × 10mm, and has 10 × 10 junction arrays, and each junction has 100μm × 100μm surface area. According to the measured data, electrical resistivitives of thin films are almost 5 times greater than those of bulk materials. This is based on the comparison of thermal simulation and measured data of 1-D heat conduction in steady state. Seebeck coefficients between copper bulk material and constantan thin film are calculated and the weight factor is defined due to Seebeck coefficient mismatches of bulk materials and thin films. Thermal simulation of 2-dimensional heat conduction in steady state calculated by finite element analysis and compared with the measured data, resulting in a good agreement between simulations and measured data.

Design of Micro-Temperature Sensor Array With Thin Film Thermocouples

2004 ◽  
Vol 127 (3) ◽  
pp. 286-289 ◽  
Author(s):  
Jong-Jin Park ◽  
Minoru Taya
Keyword(s):  
Thin Film ◽  
Heat Conduction ◽  
Steady State ◽  
Silicon Substrate ◽  
Temperature Sensor ◽  
Sensor Array ◽  
State Heat ◽  
Finite Element Analysis Simulation ◽  
Thin Film Thermocouples ◽  
Steady State Heat

We are in the process of developing a micro-temperature sensor array with T-type (copper–constantan) thin film thermocouples (TFTCs) to measure the chip temperature distribution of electronic packages. A thin aluminum nitride (AlN) layer of 100 nm thickness was deposited on a silicon substrate. AlN acts not only as an electrical insulator but also as a thermal conductor between the silicon substrate and thin film thermocouples. Copper thin film with a thickness of 50 nm and constantan thin film with the same thickness were deposited on the AlN layer. The sensor array has 10×10 junctions within a 9mm×9mm area, and each junction covers a 100μm×100μm area. Electro-thermal forces measured by TFTCs using one-dimensional steady-state heat conduction were compared with the electro-thermal forces measured by standard thermocouples, and the difference between the Seebeck coefficients of the copper material and the constantan thin film was calculated according to these measurements. In order to verify the sensor array, it was placed under two-dimensional steady-state heat conduction, and electro-thermal forces were measured and converted to temperatures. Finite element analysis simulation results were compared with the temperatures, and with experimental measurements were found to be in agreement with the simulated values.

Studies on Water in the Hydration Chamber of a Modified Electron Microscope

1970 ◽  
Vol 28 ◽  
pp. 544-545
Author(s):  
R. C. Moretz ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electron Microscope ◽  
Steady State ◽  
Room Temperature ◽  
Small Mass ◽  
Equilibrium Pressure ◽  
Biological Objects ◽  
Mechanical Pump ◽  
Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

Studies of thin film ferroelectrics with charge-compensated substitutions in BST

2002 ◽  
Vol 720 ◽  
Author(s):  
Daniel Potrepka ◽  
Steven Tidrow ◽  
Arthur Tauber ◽  
Kevin Kirchner ◽  
Bernard Rod ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Bulk Materials ◽  
Dielectric Characterization ◽  
Deposition Techniques

AbstractThin films were prepared from bulk targets by pulsed-laser deposition techniques. The targets were composed of Ba0.6Sr0.4TiO3 with charge-compensated substitutions for Ti4+. Results of the dielectric characterization measurements will be discussed and compared to the results of similar measurements in bulk materials with the same composition.

Thin Film Infrared Laser Pyrolysis Studies of Thermal Decomposition Mechanisms in Nitramine Propellants

1992 ◽  
Vol 296 ◽  
Author(s):  
Tod R. Botcher ◽  
Charles A. Wight
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Decomposition ◽  
Heat Conduction ◽  
Reaction Mechanism ◽  
Laser Pulse ◽  
Vapor Deposition ◽  
Pyrolysis Product ◽  
Initial Reaction ◽  
Reaction Products

AbstractThin films of RDX (1,3,5-trinitro-1,3,5-triazine) have been prepared by vapor deposition onto a 77 K substrate window and pyrolyzed with a pulsed CO2 laser. Each sample is rapidly quenched after the laser pulse by heat conduction into the cold substrate, and the initial reaction products are trapped on the window for examination by transmission FTIR spectroscopy. We have detected N2O4, the dimer of nitrogen dioxide, as an initial condensed phase pyrolysis product, confirming that scission of one of the N-N bonds is the first step in the reaction mechanism. No evidence was found for formation of methylene nitramine via a proposed concerted depolymerization pathway.

scholarly journals High Temperature Annealing Studies on the Piezoelectric Properties of Thin Aluminum Nitride Films

2007 ◽  
Vol 1052 ◽  
Author(s):  
R. Farrell ◽  
V. R. Pagán ◽  
A. Kabulski ◽  
Sridhar Kuchibhatla ◽  
J. Harman ◽  
...  
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Aluminum Nitride ◽  
Piezoelectric Response ◽  
Ambient Environment ◽  
High Temperature Furnace ◽  
Thin Aluminum ◽  
Controlled Environments ◽  
Temperature Furnace

AbstractA Rapid Thermal Annealing (RTA) system was used to anneal sputtered and MOVPE-grown Aluminum Nitride (AlN) thin films at temperatures up to 1000°C in ambient and controlled environments. According to Energy Dispersive X-Ray Analysis (EDAX), the films annealed in an ambient environment rapidly oxidize after five minutes at 1000°C. Below 1000°C the films oxidized linearly as a function of annealing temperature which is consistent with what has been reported in literature [1]. Laser Doppler Vibrometry (LDV) was used to measure the piezoelectric coefficient, d33, of these films. Films annealed in an ambient environment had a weak piezoelectric response indicating that oxidation on the surface of the film reduces the value of d33. A high temperature furnace has been built that is capable of taking in-situ measurements of the piezoelectric response of AlN films. In-situ d33 measurements are recorded up to 300°C for both sputtered and MOVPE-grown AlN thin films. The measured piezoelectric response appears to increase with temperature up to 300°C possibly due to stress in the film.

Monte Carlo Simulation of Steady-State Microscale Phonon Heat Transport

2008 ◽  
Vol 130 (7) ◽  
Author(s):  
Jaona Randrianalisoa ◽  
Dominique Baillis
Keyword(s):  
Heat Transfer ◽  
Thin Films ◽  
Monte Carlo ◽  
Heat Conduction ◽  
Steady State ◽  
Monte Carlo Method ◽  
Silicon Nanowires ◽  
Silicon Film ◽  
Relaxation Times ◽  
Phonon Transport

Heat conduction in submicron crystalline materials can be well modeled by the Boltzmann transport equation (BTE). The Monte Carlo method is effective in computing the solution of the BTE. These past years, transient Monte Carlo simulations have been developed, but they are generally memory demanding. This paper presents an alternative Monte Carlo method for analyzing heat conduction in such materials. The numerical scheme is derived from past Monte Carlo algorithms for steady-state radiative heat transfer and enables us to understand well the steady-state nature of phonon transport. Moreover, this algorithm is not memory demanding and uses very few iteration to achieve convergence. It could be computationally more advantageous than transient Monte Carlo approaches in certain cases. Similar to the famous Mazumder and Majumdar’s transient algorithm (2001, “Monte Carlo Study of Phonon Transport in Solid Thin Films Including Dispersion and Polarization,” ASME J. Heat Transfer, 123, pp. 749–759), the dual polarizations of phonon propagation, the nonlinear dispersion relationships, the transition between the two polarization branches, and the nongray treatment of phonon relaxation times are accounted for. Scatterings by different mechanisms are treated individually, and the creation and/or destruction of phonons due to scattering is implicitly taken into account. The proposed method successfully predicts exact solutions of phonon transport across a gallium arsenide film in the ballistic regime and that across a silicon film in the diffusion regime. Its capability to model the phonon scattering by boundaries and impurities on the phonon transport has been verified. The current simulations agree well with the previous predictions and the measurement of thermal conductivity along silicon thin films and along silicon nanowires of widths greater than 22nm. This study confirms that the dispersion curves and relaxation times of bulk silicon are not appropriate to model phonon propagation along silicon nanowires of 22nm width.

Phonon Wave Heat Conduction in Thin Films and Superlattices

1999 ◽  
Vol 121 (4) ◽  
pp. 945-953 ◽  
Author(s):  
G. Chen
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Heat Conduction ◽  
Ray Tracing ◽  
Thermal Conductance ◽  
Single Layer ◽  
Ray Tracing Method ◽  
Conductivity Of Thin Films ◽  
Tracing Method

Heat conduction in thin films and superlattices is important for many engineering applications such as thin-film based microelectronic, photonic, thermoelectric, and thermionic devices. Past modeling efforts on the thermal conductivity of thin films were based on solving the Boltzmann transport equation that treats phonons as particles. The effects of phonon interference and tunneling on the heat conduction and the thermal conductivity of thin films and superlattices remain to be explored. In this work, the wave effects on the heat conduction in thin films and superlattices are studied based on the consideration of the acoustic wave propagation in thin film structures and neglecting the internal scattering. A transfer matrix method is used to calculate the phonon transmission and heat conduction through these structures. The effects considered in this work include the phonon interference, tunneling, and confinement. The phonon dispersion is considered by introducing frequency-dependent Lamb constants. A ray-tracing method that treats phonons as particles is also developed for comparison. Sample calculations are performed on double heterojunction structures resembling Ge/Si/Ge and n-period superlattices similar to Ge/Si/n(Si/Ge)/Ge, It is found that phonon confinements caused by the phonon spectra mismatch and by the total internal reflection create a dramatic decrease of the overall thermal conductance of thin films. The phonon interference in a single layer does not have a strong effect on its thermal conductance but for superlattice structures, the stop bands created by the interference effects can further reduce the thermal conductance. Tunneling of phonon waves occurs when the constituent layers are 1–3 monolayer thick and causes a slight recovery in the thermal conductance when compared to thicker layers. The thermal conductance obtained from the ray tracing and the wave methods approaches the same results for a single layer. For superlattices, however, the wave method leads to a finite thermal conductance even for infinitely thick superlattices while the ray tracing method gives a thermal conductance that decreases with increasing number of layers. Implications of these results on explaining the recent thermal conductivity data of superlattices are explored.

The Development of the Micro-Generator on the Substrate Based Thin Film

2008 ◽  
Author(s):  
Jun-Ichiro Kurosaki ◽  
Saburo Tanaka ◽  
Koji Miyazaki ◽  
Hiroshi Tsukamoto
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Silicon Nitride ◽  
Temperature Difference ◽  
Thermoelectric Generator ◽  
Heat Radiation ◽  
Large Temperature ◽  
Substrate Thickness ◽  
Bulk Materials ◽  
Film Substrate

We fabricated bismuth-telluride based thin films and their in-plane thermoelectric micro-generators (4mm×4mm) on a glass substrate by using the flash evaporation method through shadow masks. We prepared fine powders of Bi2.0Te2.7Se0.3 (n-type) and Bi0.4Te3.0Sb1.6 (p-type). The shadow masks are fabricated by standard micro-fabrication processes such as nitridation of silicon, dry etching and wet etching. The output voltages of micro-generators are lower than that of a thermoelectric generator based on bulk materials. The main reason is because the temperature difference between cool and hot junctions of the micro-generator is small compared to a thermoelectric generator based on bulk materials. In this study, the micro-generators were fabricated on a silicon nitride substrate based thin film. By fabricating the micro-generator on the thin film substrate, a large temperature difference between cool and hot junctions is obtained due to the thin film effect and the heat radiation to air of the thin film substrate. At the silicon nitride substrate based thin films, the thermal conductivity is significantly reduced by 1.2 W/ (m K). The thin film substrate is prepared by applying the fabrication processes used for shadow masks. The silicon nitride substrate based thin film is fabricated by nitridation of silicon and then back etching the silicon wafer. The fabricated substrate thickness is 2.5 μm and 4.5 μm (4 mmx4 mm). The temperature between cool and hot junctions is measured by using the noncontact thermometer which senses the far-infrared radiation. The output voltage of the micro-generator based thin film is measured by giving a temperature difference by heating the bottom of the silicon nitride substrate based thin film.

High Quality AlN Thin Films Deposited by Middle-Frequency Magnetron Sputtering at Room Temperature

2014 ◽  
Vol 787 ◽  
pp. 227-231 ◽  
Author(s):  
Chuan Li ◽  
Lin Shu ◽  
Li Jun He ◽  
Xing Zhao Liu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Residual Stress ◽  
Aluminum Nitride ◽  
Buffer Layer ◽  
Room Temperature ◽  
Residual Tensile Stress ◽  
High Quality ◽  
Polycrystalline Aluminum ◽  
Aln Buffer

A study of depositing high quality c-axis oriented polycrystalline aluminum nitride thin film at room temperature was presented. Aluminum nitride films were grown by mid-frequency (MF) reactive sputtering. Metallic aluminum target was used to deposit AlN films in Ar/N2 gas mixture. A 50nm thick of N-rich AlN buffer layer was deposited at the initial stage of sputtering process to improve the film quality. The composition, preferred orientation and residual stress of the films were analyzed by EDS, XRD and Raman microscope, respectively. The results showed that the N-rich AlN buffer layer improved the textured degree and reduced the residual stress significantly of the AlN thin films. The near stoichiometric AlN thin film with highly textured degree was obtained. The FWHM value of the rocking curve for (0002) diffraction peak was about 1.6°, and the residual tensile stress was about 500MPa. The piezoelectric d33 coefficient increased with the decreasing of FWHM value, and the highest d33 coefficient of 3.6 pF/C was obtained.

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