Luigia Lanni

500

Successful operation of low-voltage 4H-SiC n-p-n bipolar transistors and digital integrated circuits based on emitter coupled logic is reported from -40 °C to 500 °C. Nonmonotonous temperature dependence (previously predicted by simulations but now measured) was observed for the transistor current gain; in the range -40 °C-300 °C it decreased when the temperature increased, while it increased in the range 300 °C-500 °C. Stable noise margins of ~ 1 V were measured for a 2-input OR/NOR gate operated on -15 V supply voltage from 0 °C to 500 °C for both OR and NOR output.

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Operation up to 300 ^°C of low-voltage 4H-SiC n-p-n bipolar transistors and digital integrated circuits based on emitter-coupled logic is demonstrated. Stable noise margins of about 1 V are reported for a two-input or- nor gate operated on - 15 V supply voltage from 27 ^°C up to 300 ^°C. In the same temperature range, an oscillation frequency of about 2 MHz is also reported for a three-stage ring oscillator.

Bipolar Integrated OR/NOR Gate in 4H-SiC

A monolithic bipolar operational amplifier (opamp) fabricated in 4H-SiC technology is presented. The opamp has been used in an inverting negative feedback amplifier configuration. Wide temperature operation of the amplifier is demonstrated from 25°C to 500°C. The measured closed loop gain is around 40 dB for all temperatures whereas the 3 dB bandwidth increases from 270 kHz at 25°C to 410 kHz at 500°C. The opamp achieves 1.46 V/μs slew rate and 0.25% total harmonic distortion. This is the first report on high temperature operation of a fully integrated SiC bipolar opamp which demonstrates the feasibility of this technology for high temperature analog integrated circuits.

Design and Characterization of High-Temperature ECL-Based Bipolar Integrated Circuits in 4H-SiC

Performance of 4H-SiC BJTs fabricated on a single 100mm wafer with different SiC etching and sacrificial oxidation procedures is compared in terms of peak current gain in relation to base intrinsic sheet resistance. The best performance was achieved when device mesas were defined by inductively coupled plasma etching and a dry sacrificial oxide was grown at 1100 °C.

A Monolithic, 500 °C Operational Amplifier in 4H-SiC Bipolar Technology

In this paper, we demonstrate a fully integrated linear voltage regulator in silicon carbide NPN bipolar transistor technology, operational from 25°C up to 500°C. For 15-mA load current, this regulator provides a stable output voltage with <;2% variation in the temperature range 25°C-500°C. For both line and load regulations, degradation of 50% from 25°C to 300°C and improvement of 50% from 300°C to 500°C are observed. The transient response measurements of the regulator show robust behavior in the temperature range 25°C-500°C.

SiC Etching and Sacrificial Oxidation Effects on the Performance of 4H-SiC BJTs

The effect of passivation oxide thickness and layout on the current gain of SiC bipolar junction transistors is reported. Different thicknesses of plasma enhanced chemical vapor deposited (PECVD) silicon dioxide in the range 50-150 nm were deposited prior to the same annealing process in N2O, and their effect on the transistor gain was investigated for different device layouts. For a fixed device layout, ~60 % higher gains were observed for oxide thicknesses ranging between 100 and 150 nm with current gains of ~200 at room temperature and >100 at 300 °C. For each tested thickness of deposited oxide, device layout providing lower collector resistance achieved slightly higher gains.

500 °C Bipolar SiC Linear Voltage Regulator

Three fully integrated bandgap voltage references (BGVRs) have been demonstrated in a 4H-SiC bipolar technology. The circuits have been characterized over a wide temperature range from 25 °C to 500 °C. The three BGVRs are functional and exhibit 46 ppm/°C, 131 ppm/°C, and 120 ppm/°C output voltage variations from 25 °C up to 500 °C. This letter shows that SiC bipolar BGVRs are capable of providing stable voltage references over a wide temperature range.

Influence of Passivation Oxide Thickness and Device Layout on the Current Gain of SiC BJTs

Two versions of Schmitt trigger, an emitter-coupled and an operational amplifier (opamp)-based, are implemented in 4H-SiC bipolar technology and tested up to 500 °C. The former benefits the simplicity, smaller footprint, and fewer number of devices, whereas the latter provides better promise for high temperature applications, thanks to its more stable temperature characteristics. In addition, the measurements in the range 25 °C - 500 °C, shows that the opamp-based version provides negative and positive slew rates of 4.8 V/µs and 8.3 V/µs, ~8 and ~3 times higher than that of the emitter-coupled version, which are 1.7 V/µs and 1 V/µs.

Wide Temperature Range Integrated Bandgap Voltage References in 4H–SiC

Silicon Carbide (SiC) is an excellent candidate for high temperature electronics applications, thanks to its wide bandgap. SiC power BJTs are commercially available nowadays, and it is demanding to drive them efficiently. This paper reports on the design, layout specifics, and measurements results of a SiC drive integrated circuit (IC) designed for driving SiC power BJTs. The circuit has been tested in different loading conditions (resistive and capacitive), at switching frequencies up to 500kHz, and together with a commercial power BJT. The SiC drive IC is shown to have a robust operation over the entire temperature range from 25 °C to 500 °C.

Design and characterization of 500°c schmitt trigger in 4H-SiC

Integrated digital circuits, fabricated in a bipolar SiC technology, have been successfully tested up to 600 °C. Operated with-15 V supply voltage from 27 up to 600 °C OR-NOR gates exhibit stable noise margins of about 1 or 1.5 V depending on the gate design, and increasing delay-power consumption product in the range 100 - 200 nJ. In the same temperature range an oscillation frequency of about 1 MHz is also reported for an 11-stage ring oscillator.