Wide band gap semiconductor has attracted significant industrial interest over the past decade with its superior properties: such as high critical electrical field, high thermal conductivity andwide band gap. Meanwhile many industries operating in harsh environments have long had demands for sensing solutions that function at high temperature. Current commercially available silicon-based temperature sensing IC has measure range limited to 155°C . This research work aims to develop a temperature sensor based on 4H silicon carbide with pronounced higher measurement range but comparable linearity. Furthermore, this work introduces silicon carbide based bipolar junction transistor (BJT) technology in the Else Kooi Lab (EKL).
Ratio-metric measurement technique from CMOS technology is adapted to eliminate PN diode and BJT’s non-linearity as a temperature sensor; and devices are implemented experimentally on epitaxial 4H-silicon carbide wafers in the EKL.
The characterization data shows that diode version sensor operates to 400 °C with a R2 value of 0.9963, the sensitivity under 1 mA constant current source is 4.8mV/°C . The BJT version operates to 200 °C with a R2 of 0.9965. In the future the sensor’s integration with pressure, gas, and other types of sensing solutions can provide a comprehensive sensing package. Such a package can be used to predict life time of critical components in harsh environment installations; and hence reduce the maintenance cost. Examples
of application scenarios include oil&gas exploration, industrial furnaces, geothermal extraction,and so on.

The objective of the project is to design a system which can control the temperature of a va-porizing liquid microthruster (VLM). The liquid in a VLM is heated using a heater resistor.This resistor will be used to both heat the liquid and measure the temperature.In this thesis the subsystem responsible for the measurements and the conversion of the mea-sured signals to the digital domain will be discussed. We propose a method where short measure-ment current pulses of a fixed amplitude are applied to the heater resistor. As an optimization,these pulses are omitted when a certain current threshold has been met.Results show that the system can measure temperature with±1◦C accuracy, however more fullsystem measurements are required to ensure functionality as a whole.

This thesis presents the design of an accurate current source for MEMS vaporizing liquid microthrusters. An analysis of different power supplies is presented. The design choices leading to the implemented current sink topology is given. The main components, which are an op-amp, a MOSFET and a resistor, are analyzed extensively. System integration tests showed that the current source worked adequately. The current source has also been tested separately and the imposed accuracy requirement is not met. The reason for this has to be further investigated, as there are many potential sources of errors which can cause deviations in the order of microampere. Lastly, several recommendations are given for improving the system.