Chapters authored
Impact of Dielectric Formation and Processing Techniques on the Operation of 4H-SiC MOSFETs
The mobility of carriers in the channel of silicon carbide is significantly lower than in equivalent silicon devices. This results in a significant increase in on-state resistance in comparison to theoretical predictions and is hindering the uptake of silicon carbide technology in commercial circuits. The density of interface traps at the interface between silicon carbide and the dielectric film is higher and this is often considered to be the primary reason for the low mobility. In this work, we show that the mobility is dominated by the surface roughness of the silicon carbide, especially when the transistor is operating in the strong inversion regime, by careful examination of the characteristics of lateral transistors designed to form complimentary MOS functions.
Part of the book: Advanced Silicon Carbide Devices and Processing
Self-Oscillatory DC-DC Converter Circuits for Energy Harvesting in Extreme Environments
A novel self-starting converter circuit technology is described for energy harvesting and powering wireless sensor nodes, constructed from silicon carbide devices and proprietary high temperature passives for deployment in hostile environments. After a brief review of the advantages using Silicon Carbide (SiC) over other semiconductors in extreme environments, the chapter will describe the advantages and principles when designing circuitry and architectures using SiC for power electronics. The practical results from a novel self-starting DC-DC converter are reported, which is designed to supply power to a WSN for deployment in high temperature environments. The converter operates in the boundary between continuous and discontinuous mode of operation and has a Voltage Conversion Ratio (VCR) of 3 at 300°C. This topology is able to self-start and so requires no external control circuitry, making it ideal for energy harvesting applications, where the energy supply may be intermittent. Experimental results for the self-starting converter operating from room temperature up to 300°C are presented. The converter output voltage, switching frequency, total power loss and efficiency were presented at temperatures up to 300°C.
Part of the book: Advanced Electronic Circuits