Reza Ghandi

Silicon Carbide Integrated Circuits With Stable Operation Over a Wide Temperature Range

In this letter, silicon carbide MOSFET-based integrated circuits have been designed, fabricated, and successfully tested from -193 °C (80 K) to 500 °C. Silicon carbide single MOSFETs remained fully operational over a 700-°C wide temperature range and exhibited stable I-V characteristics. The circuits that include operational amplifier (op-amp), 27-stage ring oscillator, and buffer were tested and shown to be functional up to 500 °C with relatively small performance variation between 300 °C and 500 °C. High-temperature evaluation of these circuits confirmed stable operation and survivability of both the ring oscillator and op-amp for more than 100 h at 500 °C.

Reliability of SiC Digital Telemetry Circuits on AlN Substrate

In this work, two silicon carbide based integrated circuits (frequency counter and timing generator) have been designed, fabricated, and tested for functionality at 300°C and prove to operate continuously for more than 1,000 h. Further, the boards were subjected to random vibration at 20G RMS and also mechanical shock at 215G in a 300°C environment and remained operational after 8 h of vibration and 1,000 shocks. These boards are the building blocks of a digital telemetry module for the purpose of sensing and transmitting pressure measurements from a geothermal well at temperatures up to 300°C. The frequency counter consists of one 4-bit counter, one 4-bit shift register, and one buffer. The timing generator contains an 8-bit counter, a D-flip-flop, and some dedicated logic gates to generate timing pulses for the two channel frequency counter. These dice were flip-chip bonded to patterned gold thin-film aluminum nitride substrate circuit boards.

500°C Silicon Carbide MOSFET-Based Integrated Circuits

In this work silicon carbide MOSFET based integrated circuits such as operational amplifier. 27-stage ring oscillator and CMOS-based inverter have been designed, fabricated and successfully tested at high temperatures. Silicon carbide MOSFETs remained fully operational from room temperature to 500°C with stable I-V characteristics. Also 27-stage ring oscillator, operational amplifier and CMOS inverter tested and shown to be functional up to 500°C, with relatively small performance change between 300°C and 500°C. High temperature reliability evaluation of these circuits demonstrate stable operation and both the ring oscillator and OpAmp survived more than 100 hours at 500°C.

Electronic packaging of SiC MOSFET-based devices for reliable high temperature operation

Silicon carbide (SiC) devices allow electronics to operate at high junction temperatures (>200°C) and high voltages (>10 kV). In addition, they provide faster switching and lower power losses than their silicon-based counterparts. Recently, MOSFET (metal-oxide semiconductor field effect transistor) devices were demonstrated to work up to 500°C. Robust packaging solutions are needed to take advantage of the extreme temperature capability in the areas of propulsion, power generation, and oil/natural gas exploration. This paper reviews the current packaging challenges for 400-500°C operation temperature, and presents a hermetic package solution for reliable operation.

A silicon carbide integrated circuit implementing nonlinear-carrier control for boost converter applications

The properties of silicon carbide (SiC) integrated circuit (IC) processes are discussed and nonlinear-carrier control is proposed as a controller topology that can work within the design challenges presented by SiC. A boost converter with NLC controller is demonstrated using circuit blocks built with SiC IC models.

Designing silicon carbide NMOS integrated circuits for wide temperature operation

Designing integrated circuits using silicon carbide (SiC) MOSFETs for operation in a wide temperature range brings unique challenges that require a good understanding of device characteristics, careful analysis of device-circuit interactions and a fresh look at what the technology can and cannot do. We describe the available devices in General Electrics SiC MOSFET-based technology, and use common-source amplifiers as examples in the context of designing a circuit for a wide temperature range from 25 C to 500 C.

Fabrication of 2.5kV 4H-SiC PiN Diodes with High Energy Implantation (>12MeV) of Al+ and B+

In this work, >2kV PiN diodes with >10um deep implant of B+ and 6um deep implant of Al+ have been fabricated to evaluate the quality of resulting pn junction after high-energy implantation. Acceptable low leakage currents at reverse bias and stable avalanche breakdown were observed for high energy implanted diodes (HEI-diodes) when compared to No-HEI-diodes that suggests minimal defect sites present after activation anneal.

A signal conditioning unit for high temperature applications

This paper covers the design and testing of a high temperature signal conditioning unit for integration with temperature and strain gauge sensors. The developed signal conditioning unit system includes an instrumentation amplifier, a single-ended to differential converter, an Analogue to Digital converter, and an ARINC 429 transmitter. This unit was designed and fabricated on 1 μm Silicon-on-Insulator CMOS (Complementary Metal Oxide Semiconductor) technology and has been characterized up to 225 degrees Celsius.

Optimization of high voltage SiC PiN diode for operation in opening switch mode

A high-voltage silicon carbide (SiC) PiN diode that was primarily designed to operate as a rectifier in energy conversion systems was evaluated in an opening switch mode by testing it in inductive storage circuit. Based on obtained experimental data, a mixed-mode simulation model which includes the circuit topology and the device structure, was created and validated. Numerical simulations of a diode structure optimized for operation in an opening switch mode was performed.

Multipoint temperature and pressure sensing system for monitoring CO 2 sequestration wells

We describe a novel interrogation scheme that enables multipoint measurement of temperature and pressure in harsh environment CO2 sequestration wells. Measured MEMS sensor responses are compared with finite element modeling to suggest accuracies better than ±0.1% for downhole pressure measurements.