Worlds first graphene-based Pirani pressure sensor is presented. Due to the decreased area and low thickness, the graphene-based Pirani pressure sensor allows for low power applications down to 0.9 mW. Using an innovative, transfer-free process, suspended graphene beams are realized. This allows for up to 100x miniaturization of the pressure sensor area, while enabling wafer-scale fabrication. The response of the miniaturized pressure sensor is similar to that of the much larger state-of-the-art Si-based Pirani pressure sensors, demonstrating the potential of graphene-based Pirani sensors.

The wide bandgap of silicon carbide (SiC) has attracted a large interest over the past years in many research fields, such as power electronics, high operation temperature circuits, harsh environmental sensing, and more. To facilitate research on complex integrated SiC circuits, ensure reproducibility, and cut down cost, the availability of a low-voltage SiC technology for integrated circuits is of paramount importance. Here, we report on a scalable and open state-of-the-art SiC CMOS technology that addresses this need. An overview of technology parameters, including MOSFET threshold voltage, subthreshold slope, slope factor, and process transconductance, is reported. Conventional integrated digital and analog circuits, ranging from inverters to a 2-bit analog-to-digital converter, are reported. First yield predictions for both analog and digital circuits show great potential for increasing the amount of integrated devices in future applications.

The operating principle of Pirani pressure sensors is based on the pressure dependence of a suspended strip's electrical conductivity, caused by the thermal conductance of the surrounding gas which changes the Joule heating of the strip. To realize such sensors, not only materials with high temperature dependent electrical conductivity are required, but also minimization of the suspended strip dimensions is essential to maximize the responsivity and minimize the power consumption. Due to this, nanomaterials are especially attractive for this application. Here, we demonstrate the use of a multi-layer suspended graphene strip as a Pirani pressure sensor and compare its behavior with existing models. A clear pressure dependence of the strip's electrical resistance is observed, with a maximum relative change of 2.75% between 1 and 1000 mbar and a power consumption of 8.5 mW. The use of graphene enables miniaturization of the device footprint by 100 times compared to state-of-the-art. Moreover, miniaturization allows for lower power consumption and/or higher responsivity and the sensor's nanogap enables operation near atmospheric pressure that can be used in applications such as barometers for altitude measurement. Furthermore, we demonstrate that the sensor response depends on the type of gas molecules, which opens up the way to selective gas sensing applications. Finally, the graphene synthesis technology is compatible with wafer-scale fabrication, potentially enabling future chiplevel integration with readout electronics.

This work demonstrates the first on-chip UV optoelectronic integration in 4H-SiC CMOS, which includes an image sensor with 64 active pixels and a total of 1263 transistors on a 100 mm2 chip. The reported image sensor offers serial digital, analog, and 2-bit ADC outputs and operates at 0.39 Hz with a maximum power consumption of 60 μW, which are significant improvements over previous reports. UV optoelectronics have applications in flame detection, satellites, astronomy, UV photography, and healthcare. The complexity of this optoelectronic system paves the way for new applications such harsh environment microcontrollers.

No abstract