Investigation of SiC Trench MOSFETs’ Reliability under Short-Circuit Conditions

In this paper, the short-circuit robustness of 1200 V silicon carbide (SiC) trench MOSFETs with different gate structures has been investigated. The MOSFETs exhibited different failure modes under different DC bus voltages. For double trench SiC MOSFETs, failure modes are gate failure at lower dc bus voltages and thermal runaway at higher dc bus voltages, while failure modes for asymmetric trench SiC MOSFETs are soft failure and thermal runaway, respectively. The shortcircuit withstanding time (SCWT) of the asymmetric trench MOSFET is higher than that of the double trench MOSFETs. The thermal and mechanical stresses inside the devices during the short-circuit tests have been simulated to probe into the failure mechanisms and reveal the impact of the device structures on the device reliability. Finally, post-failure analysis has been carried out to verify the root causes of the device failure.

A Failure Analysis Case of Regeneration Gas Heater Leakage

In this paper, the physical and chemical analysis method was used to analyze the leakage of a regeneration gas heater device accident. The result shows that this device was heated seriously at local area, and oxidized severely. The carbon content around the leakage is obviously lower than the limit of standard, and the grain deformation at crack tip of the leakage is obvious.It shows that reason of device failure is caused by typical plastic Instability, and low carbon content leads to insufficient mechanical properties at high temperature. According to data from manufacturer, the unreasonable arrangement of thermo-couples may be the root cause of this leakage.It can be considered that replace the higher grade materials conservatively, while optimizing the arrangement of thermo-couples.

On-Orbit Implementation of Discrete Isolation Schemes for Improved Reliability of Serial Communication Buses

Serial communication buses are used in electronic systems to interconnect sensors and other devices, but two of the most widely used protocols, I²C and SPI, are vulnerable to bus-wide failures if even one device on the bus malfunctions. For aerospace applications demanding increasingly more distributed processing and sensing capability, the compounding risk to system reliability as device count scales becomes a limiting factor in mission scope, performance, and lifetime. We propose a simple external circuit to be added to each node on a communication bus that automatically isolates the node in the event of device failure. By automatically isolating failed devices, the integrity of the bus is preserved without requiring additional signals or processing overhead from the host controller. In this article, I²C and SPI isolation circuits are simulated, fabricated, and experimentally verified to be effective at preserving bus integrity in the event of peripheral device failure. Generalized reusable circuit blocks were designed and integrated into three spacecraft systems for the successful NASA V-R3x mission deployed in January 2021. The addition of serial bus isolation significantly improved system reliability for the V-R3x mission by eliminating single-point failure modes of the I²C and SPI buses interconnecting sensors and radios necessary for mission success. The developed protection schemes are a new tool for decoupling system reliability from serial bus device count and can readily be integrated into existing aerospace systems.

High Power Normally-OFF GaN/AlGaN HEMT with Regrown p Type GaN

In this paper is presented a Normally-OFF GaN HEMT (High Electron Mobility Transistor) device using p-doped GaN barrier layer regrown by CBE (Chemical Beam Epitaxy). The impact of the p doping on the device performance is investigated using TCAD simulator (Silvaco/Atlas). With 4E17 cm−3 p doping, a Vth of 1.5 V is achieved. Four terminal breakdowns of the fabricated device are investigated, and the origin of the device failure is identified.

On-Orbit Implementation of Discrete Isolation Schemes for Improved Reliability of Serial Communication Buses

Serial communication buses are used in electronic systems to interconnect sensors and other devices, but two of the most widely used protocols, I²C and SPI, are vulnerable to bus-wide failures if even one device on the bus malfunctions. For aerospace applications demanding increasingly more distributed processing and sensing capability, the compounding risk to system reliability as device count scales becomes a limiting factor in mission scope, performance, and lifetime. We propose a simple external circuit to be added to each node on a communication bus that automatically isolates the node in the event of device failure. By automatically isolating failed devices, the integrity of the bus is preserved without requiring additional signals or processing overhead from the host controller. In this article, I²C and SPI isolation circuits are simulated, fabricated, and experimentally verified to be effective at preserving bus integrity in the event of peripheral device failure. Generalized reusable circuit blocks were designed and integrated into three spacecraft systems for the successful NASA V-R3x mission deployed in January 2021. The addition of serial bus isolation significantly improved system reliability for the V-R3x mission by eliminating single-point failure modes of the I²C and SPI buses interconnecting sensors and radios necessary for mission success. The developed protection schemes are a new tool for decoupling system reliability from serial bus device count and can readily be integrated into existing aerospace systems.

On-Orbit Implementation of Discrete Isolation Schemes for Improved Reliability of Serial Communication Buses

Serial communication buses are used in electronic systems to interconnect sensors and other devices, but two of the most widely used protocols, I²C and SPI, are vulnerable to bus-wide failures if even one device on the bus malfunctions. For aerospace applications demanding increasingly more distributed processing and sensing capability, the compounding risk to system reliability as device count scales becomes a limiting factor in mission scope, performance, and lifetime. We propose a simple external circuit to be added to each node on a communication bus that automatically isolates the node in the event of device failure. By automatically isolating failed devices, the integrity of the bus is preserved without requiring additional signals or processing overhead from the host controller. In this article, I²C and SPI isolation circuits are simulated, fabricated, and experimentally verified to be effective at preserving bus integrity in the event of peripheral device failure. Generalized reusable circuit blocks were designed and integrated into three spacecraft systems for the successful NASA V-R3x mission deployed in January 2021. The addition of serial bus isolation significantly improved system reliability for the V-R3x mission by eliminating single-point failure modes of the I²C and SPI buses interconnecting sensors and radios necessary for mission success. The developed protection schemes are a new tool for decoupling system reliability from serial bus device count and can readily be integrated into existing aerospace systems.