Silicon carbide (SiC), a material long known with potential for high-temperature, high-power, high-frequency, and radiation hardened applications, has emerged as the most mature of the wide-bandgap (2.0 eV ≲ Eg ≲ 7.0 eV) semiconductors since the release of commercial 6HSiC bulk substrates in 1991 and 4HSiC substrates in 1994. Following a brief introduction to SiC material properties, the status of SiC in terms of bulk crystal growth, unit device fabrication processes, device performance, circuits and sensors is discussed. Emphasis is placed upon demonstrated high-temperature applications, such as power transistors and rectifiers, turbine engine combustion monitoring, temperature sensors, analog and digital circuitry, flame detectors, and accelerometers. While individual device performances have been impressive (e.g. 4HSiC MESFETs with fmax of 42 GHz and over 2.8 W mm−1 power density; 4HSiC static induction transistors with 225 W power output at 600 MHz, 47% power added efficiency (PAE), and 200 V forward blocking voltage), material defects in SiC, in particular micropipe defects, remain the primary impediment to wide-spread application in commercial markets. Micropipe defect densities have been reduced from near the 1000 cm−2 order of magnitude in 1992 to 3.5 cm−2 at the research level in 1995.

Status of silicon carbide (SiC) as a wide-bandgap semiconductor for high-temperature applications: A review

This paper provides a detailed overview of developments in transducer materials technology relating to their current and future applications in micro-scale devices. Recent advances in piezoelectric, magnetostrictive and shape-memory alloy systems are discussed and emerging transducer materials such as magnetic nanoparticles, expandable micro-spheres and conductive polymers are introduced. Materials properties, transducer mechanisms and end applications are described and the potential for integration of the materials with ancillary systems components is viewed as an essential consideration. The review concludes with a short discussion of structural polymers that are extending the range of micro-fabrication techniques available to designers and production engineers beyond the limitations of silicon fabrication technology.

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New materials for micro-scale sensors and actuators An engineering review

Gas sensors directed to high-volume applications are discussed. Mainly semiconductor sensors cover this sector, but the merits of competing devices are shown in comparison. Chemical and physical function is elucidated by spectroscopic results and molecular calculations. Important applications, e.g. monitoring of combustibles, especially methane, and the early detection of fires, are presented as illustrations. Progress in microelectronics has enhanced the development of electronic noses. An early example of such noses, the identification of solvents and also the present state of food aroma detection are described.

https://iopscience.iop.org/article/10.1088/0022-3727/34/19/201/pdf

Function and applications of gas sensors

Silicon carbide (SiC) is a material with very attractive properties for microsystems applications Its mechanical strength, high thermal conductivity, ability to operate at high temperatures and extreme chemical inertness in several liquid electrolytes, make SiC an attractive candidate for MEMS applications, both as structural material and as coating layer The recently reported progress in material growth and processing techniques has strengthened the potential of this material for MEMS, especially for applications requiring operation at high temperature or in severe environments Examples of SiC microsensors and microstructures are given and interesting development in both material characteristics and micromachining processes are discussed

Silicon carbide as a new MEMS technology

Silicon carbide (SiC) is a promising material for the development of high-temperature solid-state electronics and transducers, owing to its excellent electrical, mechanical, and chemical properties. This paper is a review of silicon carbide for microelectromechanical systems (SiC MEMS). Current efforts in developing SiC MEMS to extend the silicon-based MEMS technology to applications in harsh environments are discussed. A summary is presented of the material properties that make SiC an attractive material for use in such environments. Challenges faced in the development of processing techniques are also outlined. Last, a review of the current stare of SiC MEMS devices and issues facing future progress are presented.

Silicon carbide MEMS for harsh environments

High temperature gas sensors based on catalytic metal-insulator-silicon carbide (MISiC) devices are developed both as capacitors and Schottky diodes. A maximum operation temperature of 1000 degrees C is obtained for capacitors based on 4H-SiC, and all sensors work routinely for several weeks at 600 degrees C. Reducing gases like hydrocarbons and hydrogen lower the flat band voltage of the capacitor and the barrier height of the diode. The time constants for the gas response are in the order of milliseconds and because of this good performance the sensors are tested for combustion engine control. For temperatures around 600 degrees C total combustion occurs on the sensor surface and the signal is high for fuel in excess and low for air in excess. At temperatures around 400 degrees C the response is more linear. The high temperature operation causes interdiffusion of the metal and insulator layers in these devices; and this interdiffusion has been studied. At sufficiently high temperatures the inversion capacitance shows different levels for hydrogen free and hydrogen containing ambients, which is suggested to be due to a reversible hydrogen annealing effect at the insulator-silicon carbide interface.

High Temperature Sensors Based on Metal–Insulator–Silicon Carbide Devices

Silicon carbide (SiC) based field effect gas sensors can be operated at very high temperatures. Catalytic metal-insulator-silicon carbide (MISiC) Schottky diodes respond very fast to a change between a reducing and an oxidizing atmosphere, and cylinder-specific combustion engine monitoring has been demonstrated. The sensors have also been suggested for high-temperature electronic nose applications. Car applications and other harsh environments put very strong requirements on the long-term stability of the sensors. Here we review the current status of the field of SiC based Schottky diode gas sensors with emphasis on the work in our group. Basic work on understanding of the detection mechanism and the influence of interfacial layers on the long-term stability of the sensors is reviewed. The direction of future research and device development in our group is also discussed.

Current status of silicon carbide based high-temperature gas sensors

It is demonstrated that the current-voltage characteristics of platinum-thin insulator silicon carbide diodes react rapidly to changes of the concentration of oxygen and hydrocarbons in the ambient already at temperatures around 500/spl deg/C-600/spl deg/C. In this letter, we use moving gas outlets to, for the first time, estimate time constants of the response in the order of a few milliseconds. The short time constants of these sensors make them suitable for applications in combustion monitoring. The new method to modulate gas concentrations rapidly at surfaces has the potential to be a valuable tool for evaluation of device structures for fast chemical sensing.

Fast chemical sensing with metal-insulator silicon carbide structures

High temperature sensors, Schottky diodes and capacitors, based on catalytic metal-oxide-silicon carbide devices are investigated. Reducing gases like hydrogen and other hydrogen containing gases, ...

Influence of carbon monoxide, water and oxygen on high temperature catalytic metal-oxide-silicon carbide structures

We report on a reversible hydrogen annealing effect observed in platinum-silicon dioxide-silicon carbide structures at temperatures above about 650 degrees C. It appears as a decrease of the invers ...

Amir Baranzahi

Papers

High Temperature Sensors Based on Metal–Insulator–Silicon Carbide Devices

Current status of silicon carbide based high-temperature gas sensors

Fast chemical sensing with metal-insulator silicon carbide structures

Influence of carbon monoxide, water and oxygen on high temperature catalytic metal-oxide-silicon carbide structures

Reversible hydrogen annealing of metal‐oxide‐silicon carbide devices at high temperatures