Here a physically based channel mobility model has been developed to investigate the temperature dependence of the field-effect mobility of metal-oxide-semiconductor (MOS) transistors with thermally oxidized gate insulators. This model has been designed so that it accounts for the high density of traps at the MOS interface. This temperature dependence is a key issue for silicon carbide electronics, as its basic material properties make it the foremost semiconductor for high power/high temperature electronic devices in applications such as spacecraft, aircraft, automobile, and energy distribution. Our modeling suggests that the high density of charged acceptor interface traps, encountered in thermally grown gate oxides, modulates the channel mobility due to the Coulomb scattering of free carriers in the inversion layer. When the temperature increases, the field-effect mobility of these devices also increases, due to an increase in inversion charge and a reduction of the trapped charge. Experimental data of the field-effect mobility temperature dependence are in good agreement with this model.
For the first time, the I-V-T dataset of a Schottky diode has been accurately modelled, parameterised, and fully fit, incorporating the effects of interface inhomogeneity, patch pinch-off and resistance, and ideality factors that are both heavily temperature and voltage dependent. A Ni/SiC Schottky diode is characterised at 2 K intervals from 20 to 320 K, which, at room temperature, displays low ideality factors (n < 1.01) that suggest that these diodes may be homogeneous. However, at cryogenic temperatures, excessively high (n > 8), voltage dependent ideality factors and evidence of the so-called “thermionic field emission effect” within a T0-plot, suggest significant inhomogeneity. Two models are used, each derived from Tung's original interactive parallel conduction treatment of barrier height inhomogeneity that can reproduce these commonly seen effects in single temperature I-V traces. The first model incorporates patch pinch-off effects and produces accurate and reliable fits above around 150 K, and at current densities lower than 10−5 A cm−2. Outside this region, we show that resistive effects within a given patch are responsible for the excessive ideality factors, and a second simplified model incorporating these resistive effects as well as pinch-off accurately reproduces the entire temperature range. Analysis of these fitting parameters reduces confidence in those fits above 230 K, and questions are raised about the physical interpretation of the fitting parameters. Despite this, both methods used are shown to be useful tools for accurately reproducing I-V-T data over a large temperature range.
19 May 2017 in IEEE Journal of the Electron Devices Society
A method to improve thermal management of β-Ga 2 O 3 FETs is demonstrated here via simulation of epitaxial growth on a 4H-SiC substrate. Using a recently published device as a model, the reduction achieved in self-heating allows the device to be driven at higher gate voltages and increases the overall performance. For the same operating parameters an 18% increase in peak drain current and 15% reduction in lattice temperature are observed. Device dimensions may be substantially reduced without detriment to performance and normally off operation may be achieved.
Currently, a significant portion (~50%) of global warming emissions, such as CO2, are related to energy production and transportation. As most energy usage will be electrical (as well as transportation), the efficient management of electrical power is thus central to achieve the XXI century climatic goals. Ultra-wide bandgap (UWBG) semiconductors are at the very frontier of electronics for energy management or energy electronics. A new generation of UWBG semiconductors will open new territories for higher power rated power electronics and solar-blind deeper ultraviolet optoelectronics. Gallium oxide—Ga2O3 (4.5–4.9 eV), has recently emerged pushing the limits set by more conventional WBG (~3 eV) materials, such as SiC and GaN, as well as for transparent conducting oxides (TCO), such asIn2O3, ZnO and SnO2, to name a few. Indeed, Ga2O3 as the first oxide used as a semiconductor for power electronics, has sparked an interest in oxide semiconductors to be investigated (oxides represent the largest family of UWBG). Among these new power electronic materials, AlxGa1-xO3 may provide high-power heterostructure electronic and photonic devices at bandgaps far beyond all materials available today (~8 eV) or ZnGa2O4 (~5 eV), enabling spinel bipolar energy electronics for the first time ever. Here, we review the state-of-the-art and prospects of some ultra-wide bandgap oxide semiconductor arising technologies as promising innovative material solutions towards a sustainable zero emission society.
In this paper we investigate the physical and electrical properties of silicon layers grown by molecular beam epitaxy on substrates, evaluating the effect of the Si doping, Si temperature deposition, and SiC surface cleaning procedure. monolithic integration of Si circuits with SiC power devices can be considered as an attractive proposition and has the potential to be applied to a broad range of applications. X-ray diffraction and scanning electron microscopy are used to determine the Si crystal structure (cubic silicon) and morphology. and measurements are performed to evaluate the rectifying diode characteristics along with the built-in potential and energy band offsets. In the last section, we propose that our heteojunction diode current characteristics can be explained by an isojunction drift-diffusion and thermoionic emission model where the effect of doping concentration of the silicon layer and its conduction band offset with SiC is analyzed.