No abstract

Although Silicon Carbide has become the material of choice for high power applications in a range of extreme environments, the interest in creating active chemical sensors requires the development of transistors for additional control circuits to operate in these environments. Despite the recent advances in the quality of oxide layers on SiC, the mobility of inversion layers is still low and this will affect the maximum frequency of the operation for these devices. We present simulation results which indicate that a delta channel, in both n-channel and p-channel structures, is suitable for transistors used with these low level signals. By varying the doping levels of the device we have shown that the optimum delta doping for this application is 1.43x1019 cm-3 for both n and p channel devices. We then show the effects of high temperatures on the delta FET devices and make comparisons with standard SiC MOSFET devices.

New results are presented of a surface trench defect observed during anneal of room temperature Al implants. The size of the surface defect is proportional to anneal temperature and occurs predominantly in the implanted zone. Signs of lattice strain are observed outside the implanted zone as well.

In this paper a novel approach to the design and fabrication of a high temperature inverter module for hybrid electrical vehicles is presented. Firstly, SiC power electronic devices are considered in place of the conventional Si devices. Use of SiC raises the maximum practical operating junction temperature to well over 200°C, giving much greater thermal headroom between the chips and the coolant. In the first fabrication, a SiC Schottky barrier diode (SBD) replaces the Si pin diode and is paired with a Si-IGBT. Secondly, doublesided cooling is employed, in which the semiconductor chips are sandwiched between two substrate tiles. The tiles provide electrical connections to the top and the bottom of the chips, thus replacing the conventional wire bonded interconnect. Each tile assembly supports two IGBTs and two SBDs in a half-bridge configuration. Both sides of the assembly are cooled directly using a high-performance liquid impingement system. Specific features of the design ensure that thermo-mechanical stresses are controlled so as to achieve long thermal cycling life. A prototype 10 kW inverter module is described incorporating three half-bridge sandwich assemblies, gate drives, dc-link capacitance and two heat-exchangers. This achieves a volumetric power density of 30W/cm3.

This report investigates the advantages of high-k materials as gate dielectrics for high power SiC trench MOSFET devices, by means of TCAD simulation. The study makes a comparison between the breakdown characteristics of gate dielectrics comprising SiO2, HfO2 and TiO2. I-V and Transfer functions show forward characteristics with on-state resistivity of 8.27 m*⋅cm2, 8.65 m*⋅cm2, 15.8 m*⋅cm2 for the respective devices, at a gate voltage of 20 V. The threshold voltage is 10 V for all devices. The blocking voltage for the HfO2 and TiO2 is increased from 1800 V (for the SiO2 device) to 2200 V. With a peak electric field of 12 MV/cm through the oxide of the SiO2 device is reduced to 3.2 MV/cm for the HfO2 and 2.3 MV/cm for the TiO2 devices.