Thermoelectric Power of Bi And Bi1−xSbx Alloy Thin Films And Superlattices Grown by MBE

1997 ◽  
Vol 478 ◽  
Author(s):  
Sunglae Cho ◽  
Antonio DiVenere ◽  
George K. Wong ◽  
John B. Ketterson ◽  
Jerry R. Meyer ◽  
...  

AbstractWe have measured the thermoelectric power (TEP) of MBE-grown epitaxial Bi and Bi1−xSbx alloy thin films and superlattices as a function of temperature in the range 20–300 K. We have observed that the TEP of a Bi thin film of 1 μm thickness is in good agreement with the bulk single crystal value and that the TEPs for superlattices with 400 Å and 800 Å Bi well thicknesses are enhanced over the bulk values. For x=0.072 and 0.088 in Bi1−xSbx thin films showing semiconducting behavior, TEP enhancement was observed by a factor of two. However as Bi or Bi1−xSbx well thickness decreases in superlattice geometry, the TEP decreases, which may be due to unintentional p-type doping.

Author(s):  
Koji Miyazaki ◽  
Jun-Ichiro Kurosaki ◽  
Masayuki Takashiri ◽  
Bertrand Lenoir ◽  
Hiroshi Tsukamoto

In this study, we fabricated bismuth-telluride thin films and their in-plane thermoelectric micro-coolers (4mm×4mm) by using the flash evaporation method. We prepared fine powders of Bi2.0Te2.7Se0.3 (n-type) and Bi0.4Te3.0Sb1.6 (p-type). The thermoelectric properties of as-grown thin films are lower than those of bulk materials. Therefore the as-grown thin films were annealed in hydrogen at atmospheric pressure for 1 hour in a temperature range of 200 to 400°C. By optimizing the annealing temperature, thin films with high thermoelectric power factors of 8.8 μW/(cm·K2) in n-type and 13.8 μW/(cm·K2) in p-type are obtained. To evaluate the figure of merit of the thin film, the thermal conductivity of the n-type thin film is measured by the 3ω method. The thin film annealed at 200 °C exhibited a cross-plane thermal conductivity of 1.2 W/(m·K). Micro-coolers of flash-evaporated bismuth-telluride thin films are fabricated using three shadow masks. The shadow masks are prepared by standard micro-fabrication processes such as nitridation of Si, dry etching, and wet etching. Thermoelectric power of the as-grown thin film devices with 16 pairs of p-n legs are measured by YAG laser heating at the center of the devices. The thermoelectric power of thermoelectric legs is evaluated to be 180μV/K per one p-n leg pair. According to the Kelvin’s law, it corresponds to 54mV Peltier coefficient per p-n pair.


1995 ◽  
Vol 403 ◽  
Author(s):  
T. S. Hayes ◽  
F. T. Ray ◽  
K. P. Trumble ◽  
E. P. Kvam

AbstractA refined thernodynamic analysis of the reaction between molen Al and SiC is presented. The calculations indicate much higher Si concentrations for saturation with respect to AkC 3 formation than previously reported. Preliminary microstructural studies confirm the formation of interfacial A14C3 for pure Al thin films on SiC reacted at 9000C. The implications of the calculations and experimental observations for the production of ohmic contacts to p-type SiC are discussed.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuki Tsuruma ◽  
Emi Kawashima ◽  
Yoshikazu Nagasaki ◽  
Takashi Sekiya ◽  
Gaku Imamura ◽  
...  

AbstractPower devices (PD) are ubiquitous elements of the modern electronics industry that must satisfy the rigorous and diverse demands for robust power conversion systems that are essential for emerging technologies including Internet of Things (IoT), mobile electronics, and wearable devices. However, conventional PDs based on “bulk” and “single-crystal” semiconductors require high temperature (> 1000 °C) fabrication processing and a thick (typically a few tens to 100 μm) drift layer, thereby preventing their applications to compact devices, where PDs must be fabricated on a heat sensitive and flexible substrate. Here we report next-generation PDs based on “thin-films” of “amorphous” oxide semiconductors with the performance exceeding the silicon limit (a theoretical limit for a PD based on bulk single-crystal silicon). The breakthrough was achieved by the creation of an ideal Schottky interface without Fermi-level pinning at the interface, resulting in low specific on-resistance Ron,sp (< 1 × 10–4 Ω cm2) and high breakdown voltage VBD (~ 100 V). To demonstrate the unprecedented capability of the amorphous thin-film oxide power devices (ATOPs), we successfully fabricated a prototype on a flexible polyimide film, which is not compatible with the fabrication process of bulk single-crystal devices. The ATOP will play a central role in the development of next generation advanced technologies where devices require large area fabrication on flexible substrates and three-dimensional integration.


2021 ◽  
Author(s):  
Yuki Tsuruma ◽  
Emi Kawashima ◽  
Yoshikazu Nagasaki ◽  
Takashi Sekiya ◽  
Gaku Imamura ◽  
...  

Abstract Power devices (PD) are ubiquitous elements of the modern electronics industry that must satisfy the rigorous and diverse demands for robust power conversion systems that are essential for emerging technologies including Internet of Things (IoT), mobile electronics, and wearable devices. However, conventional PDs based on “bulk” and “single-crystal” semiconductors require high temperature (>1000°C) fabrication processing and a thick (typically a few tens to 100 μm) drift layer1, thereby preventing their applications to compact devices2, where PDs must be fabricated on a heat sensitive and flexible substrate. Here we report next-generation PDs based on “thin-films” of “amorphous” oxide semiconductors with the performance exceeding the silicon limit (a theoretical limit for a PD based on bulk single-crystal silicon3). The breakthrough was achieved by the creation of an ideal Schottky interface without Fermi-level pinning at the interface, resulting in low specific on-resistance Ron,sp (<1×10-4 Ωcm2) and high breakdown voltage VBD (~100 V). To demonstrate the unprecedented capability of the amorphous thin-film oxide power devices (ATOPs), we successfully fabricated a prototype on a flexible polyimide film, which is not compatible with the fabrication process of bulk single-crystal devices. The ATOP will play a central role in the development of next generation advanced technologies where devices require large area fabrication on flexible substrates and three-dimensional integration.


2018 ◽  
Vol 6 (6) ◽  
pp. 1393-1398 ◽  
Author(s):  
Shengbin Nie ◽  
Ao Liu ◽  
You Meng ◽  
Byoungchul Shin ◽  
Guoxia Liu ◽  
...  

In this study, transparent p-type CuCrxOy semiconductor thin films were fabricated using spin coating and integrated as channel layers in thin-film transistors (TFTs).


2002 ◽  
Vol 16 (03) ◽  
pp. 473-480 ◽  
Author(s):  
JULIA M. WESSELINOWA ◽  
STEFFEN TRIMPER

Based on an Ising model in a transverse field (TIM) and using a Green's function formalism the critical exponents of the polarization β and of the longitudinal susceptibility γ are calculated for a ferroelectric thin film consisting of N layers. The exponents depends on the number of layers in a significant manner. Whereas for N=3 layers the exponents are β=0.131 and γ=1.739 there is a change over to β=0.315 and γ=1.239 in case of N=30. The datas are in a good agreement with predictions for 2D and 3D Ising systems. Using scaling laws other exponents like α, δ, η and ν are obtained, too.


2011 ◽  
Vol 254 ◽  
pp. 50-53 ◽  
Author(s):  
Tatsuya Ishii ◽  
Hideyuki Homma ◽  
Shigeo Yamaguchi

We fabricated a thin film Peltier device based on an InSb film and a SbTe film. N-type InSb thin films were grown on sapphire (0001) substrate with InAsSb buffer layer by metalorganic vapor phase epitaxy, and P-type SbTe thin films were deposited on the substrate by electron beam evaporation. N-type and P-type films were separated on the substrate, and between them, a Au thin film was deposited by direct-current sputtering. We observed partial Peltier effect in the device.


A brief review is given of the methods that are available for studying surfaces on a microscope scale. The use of finely focused scanned electron beams is described in detail. Examples are given of Auger and secondary electron spectroscopy and microscopy, and of diffraction techniques. These examples are largely taken from recent work of the authors on Ag layers on bulk single-crystal Si (111), Si (100) and W (110) surfaces, but applications to other materials and to thin films are also discussed. Future developments are briefly outlined.


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