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β-Ga2O3 is a promising ultrawide bandgap semiconductor for next generation radio frequency electronics. However, its low thermal conductivity and inherent thermal resistance provide additional challenges in managing the thermal response of β-Ga2O3 electronics, limiting its power performance. In this paper, we report the heteroepitaxial growth of β-Ga2O3 films on high thermal conductivity 4H-SiC substrates by molecular beam epitaxy (MBE) at 650 °C. Optimized MBE growth conditions were first determined on sapphire substrates and then used to grow β-Ga2O3 on 4H-SiC. X-ray diffraction measurements showed single phase (2¯01) β-Ga2O3 on (0001) SiC substrates, which was also confirmed by TEM measurements. These thin films are electrically insulating with a (4¯02) peak rocking curve full-width-at-half-maximum of 694 arc sec and root mean square surface roughness of ∼2.5 nm. Broad emission bands observed in the luminescence spectra, acquired in the spectral region between near infrared and deep ultraviolet, have been attributed to donor-acceptor pair transitions possibly related to Ga vacancies and its complex with O vacancies. The thermal conductivity of an 81 nm thick Ga2O3 layer on 4H-SiC was determined to be 3.1 ± 0.5 W/m K, while the measured thermal boundary conductance (TBC) of the Ga2O3/SiC interface is 140 ± 60 MW/m2 K. This high TBC value enables the integration of thin β-Ga2O3 layers with high thermal conductivity substrates to meliorate thermal dissipation and improve device thermal management.

The efficient use of energy is a priority when a technology migration plan is being executed. Several factors must be taken into account in order to achieve this goal. In this paper the migration from liquefied petroleum gas based cookers to electric induction cookers is analyzed, emphasizing on the selection of the best material to produce the cookware suitable for induction cookers in terms of energy saving and performance. To accomplish this study, several tests have been performed in three kind of pots made of different materials: stainless steel, cast iron and aluminium. These tests have allowed to evaluate some material properties as rust resistance, structural stability of pot bottom under thermal impact conditions, energy efficiency measurements in different body cookware materials, energy efficiency with different distances between induction zone and pot bottom, relation between energy efficiency and initial measurements of concavity/convexity and energy efficiency before and after thermal impact conditions. After completing this research, it has been found that the enameled cast iron and the stainless steel present higher efficiency in the same stove.

The quality of printable dielectric layer has become one of the major obstacles to achieving highperformance fully printed transistors. A thick dielectric layer will require high gate voltage to switch the transistors on and off, which will cause high power dissipation in printed devices. In response to this challenge, fully printed carbon nanotube (CNT)-based thin-film transistors (TFTs) have been fabricated on flexible membranes such as polyimide and liquid crystal polymer using aerosol jet printing. These devices can be operated at bias voltages below ±10 V (drain/ gate voltages around ±6 V). This is much smaller than the previously reported values for fully printed CNT-TFTs because of using xdi-dcs (mixture of poly(vinylphenol)/poly (methylsilsesquioxane)) as the dielectric and using a single printing method. The lower voltage is a consequence of a thin dielectric layer (∼300 nm) and good uniformity in the printed CNT network. The printed CNT-TFTs show on/off ratio >10 5 , and mobility >5 cm 2 V −1 s −1 . Layerby-layer deposition of CNT allows highly uniform and dense network formation, and the optimization of the xdi-dcs concentration using natural butyl alcohol provides high-yield printing of a thin dielectric layer. Collectively, this work shows the potential of using fully printed CNT-TFTs in various flexible electronic applications such as wearable sensors, actuators, artificial skin, displays and wireless tags and antennas.

En este trabajo se proponen valores de transmitancia atmosférica, utilizando la heliofanía (horas de sol) y la diferencia de temperaturas extremas diarias de una localidad de la zona ecuatorial alto andina. Para tal efecto, se calculó la radiación total extraterrestre estudiándose la confiabilidad de los modelos de energía solar total incidente. Luego se realizó un tratamiento estadístico de los valores atípicos a las variables de radiación total incidente, heliofanía y temperaturas máximas y mínimas diarias en la ciudad de Riobamba, las mismas que fueron medidas por casi cinco años desde junio del 2007. Con estos datos, se calcularon los coeficientes de correlación lineal entre las variables utilizando tres modelos: uno que usa la heliofanía y dos que utilizan las diferencias de temperaturas, observándose que existe una relación más consistente entre la radiación y la heliofanía. Además se estableció que no es adecuado generalizar los valores obtenidos para otras regiones, aunque tengan condiciones atmosféricas similares.