In this paper, we propose a temperature sensor based on a 4H-SiC CMOS oscillator circuit and that is able to operate in the temperature range between 298 K and 573 K. The circuit is developed on Fraunhofer IISB’s 2 μm 4H-SiC CMOS technology and is designed for a bias voltage of 20 V and an oscillation frequency of 90 kHz at room temperature. The possibility to relate the absolute temperature with the oscillation frequency is due to the temperature dependency of the threshold voltage and of the channel mobility of the transistors. An analytical model of the frequency-temperature dependency has been developed and is used as a starting point for the design of the circuit. Once the circuit has been designed, numerical simulations are performed with the Verilog-A BSIM4SiC model, which has been opportunely tuned on Fraunhofer IISB’s 2 μm 4H-SiC CMOS technology, and their results showed almost linear frequency-temperature characteristics with a coefficient of determination that was higher than 0.9681 for all of the bias conditions, whose maximum is 0.9992 at a $V_{DD}$ = 12.5 V. Moreover, we considered the effects of the fabrication process through a Monte Carlo analysis, where we varied the threshold voltage and the channel mobility with different values of the Gaussian distribution variance. For example, at $V_{DD}$ = 20 V, a deviation of $17.4\%$ from the nominal characteristic is obtained for a Gaussian distribution variance of $20\%$. Finally, we applied the one-point calibration procedure, and temperature errors of +8.8 K and −5.8 K were observed at $V_{DD}$ = 15 V.

The experimental characteristics of a temperature sensor based on a 4H-SiC diode-connected lateral NMOSFET are shown in the range between 14K and 481K. The device is fully compatible with 4H-SiC CMOS technology. The analysis of the sensor characteristics reveals a main temperature dependence on the threshold voltage compared to the channel mobility. Due to the oxide/semiconductor interface traps, the sensor characteristic is divided in three temperature ranges to obtain a good linearity: in 14K $\leq $ T $\leq 200$ K, the sensitivity is 53.46mV/K, the rms error is 5.49K and the coefficient of determination is 0.9927 for a bias current of $1.59\mu $ A; instead, a current of $100\mu $ A permits to have a maximum coefficient of determination of 0.9708 with a sensitivity of 29.9mV/K for 200K < T $\leq 394$ K, and a linearity of 0.9926 with a sensitivity of 13.72mV/K at T >394K. Finally, for currents between 870nA and $9\mu $ A the linearity is higher than 0.95 in all temperature ranges.

In this paper, a compact DC SPICE model for 4H-SiC lateral metal oxide semiconductor field effect transistors is shown both for PMOSFET and NMOSFET. It is validated through experimental comparisons by varying channel sizes, temperature in the range between 298K and 573K, and body voltage conditions. A new model of the threshold voltage is introduced in order to take into account the effects of the high interface defects density. Finally, an inverter logic gate is simulated at different temperatures and compared with experimental data and with BSIM4SiC simulation outcomes, where a maximum logic threshold voltage error of 0.85% to the experimental data is shown compared to 6.78% of BSIM4SiC.

A temperature sensor based on a diode-connected 4H-Silicon Carbide p-type metal oxide semiconductor field effect transistor is characterized in the temperature range between 14K and 482K and its performance has been analysed. The study shows that the sensor characteristics are mainly affected by the threshold voltage, but an unusual reduction of the device current is shown for temperatures lower than 76K, which limits the linearity of the sensor response. Indeed, two operating temperature ranges could be defined. The first one is in the range 76K ≤ T ≤ 175K, showing a linearity of 0.991 in terms of coefficient of determination and a sensitivity of 6.24mK/K at a device current of 3.34nA, instead the second range is for temperatures higher than 175K with a linearity of 0.986 and a sensitivity of 66.37mV/K for a current of 263nA. Moreover, the device is fully compatible with 4H-SiC CMOS technology making possible its use in integrated circuits.

A 4H-Silicon Carbide (4H-SiC) complementary to absolute temperature sensor is characterized and analyzed in the operating temperature range between 14 K and 481 K and is based on 4H-SiC diode-connected lateral NMOSFET. It is an integrated circuit compatible with 4H-SiC CMOS technology. The sensor characteristic has a unique linear curve from 481 K down to 150 K, for saturation, or to 100 K, for subthreshold bias regime. In both cases, the linearity is high, with a coefficient of determination, $R^{2}>0.99$, and the sensitivity varies from $-$ 1.98 to $-$ 7.7 mV/K. The analysis shows that the limitation of the single transistor T-sensor, due to the oxide/semiconductor interface traps, is overcome by applying two different bias currents, whereas at very low temperatures, the loss of linearity is due to the increase of the effective channel mobility (saturation) or to the increase of the slope of the single transcharacteristics (subthreshold).

An analysis of 4H-SiC CMOSFETs electrical characteristics is reported up to a temperature of 773 K taking into account the effects of the channel lengths, i.e., 2 and ${6}~\mu \text {m}$ , and of the physical parameters. Even though the threshold voltage and the channel mobility have similar dependencies on the geometry and temperature, they are described by quite different phenomena. For NMOSFET, the threshold voltage has a further reduction with the channel shortening and with the temperature due to 4H-SiC/SiO₂ interface defects, instead its maximum channel mobility of around ${21}.{75}~\text {cm}^{{2}}/\text {V}/\text {s}$ results almost the same up to 723K but then drastically reduces to ${14}.{28}~\text {cm}^{{2}}/\text {V}/\text {s}$ due to lattice vibration scattering. On the other hand, PMOSFET shows a hump of the threshold voltage with the reduction of the channel length, ascribing to a reverse short-channel effect, whereas the channel mobility is strongly affected by p-type parasitic series resistances. Due to the concomitant effects of the threshold voltage and of the channel mobility, the current increases with the temperature up to the range of [523–623] K, depending on the channel size, but then decreases, avoiding the thermal run-away effect.