Space radiation is a mixture of high-velocity charged particles. These particles interact with semiconductors, affecting their electrical properties and potentially causing failures.
Accumulative Effects
Total Ionization Dose (TID)
When high-energy particles traverse a semiconductor, they generate electron-hole pairs. While electrons leave quickly, holes accumulate, altering transistor properties such as threshold voltage and transmission delays. TID is measured in rads, where different technologies have varying thresholds:
- CMOS: 1-10 krad
- Radiation-hardened devices: 100 krad - 1 Mrad
- Bipolar technology: 10-100 krad
Displacement Damage Effect
High-energy particles can displace atoms in a material's crystal lattice, forming defect clusters that alter device characteristics. This primarily affects bipolar transistors, solar panels, and photoelectric devices, reducing efficiency and altering performance.
Transient Effects
Single Event Latch-up (SEL)
CMOS components contain parasitic PNPN structures. A charged particle impact can switch these structures on, causing a short circuit and potentially destroying the device. Protective circuitry is essential to detect overcurrent and cut off power.
Single Event Upset (SEU)
SEU occurs when a high-energy particle changes a digital device's state. Common effects include:
- Bit Flip: A single-bit error in memory (SEU) or multiple bits (MBU).
- Single Event Functional Interrupt (SEFI): Errors in control elements cause resets or malfunctions but are reversible without power cycling.
- Single Event Transient (SET): A brief voltage spike that may disturb analog or digital circuit operation.
Damage to Power Components
Single Event Burnout (SEB)
Occurs in MOSFET transistors when a high-energy particle activates a parasitic bipolar transistor, causing an overcurrent that breaks down the MOSFET.
Single Event Gate Rupture (SEGR)
High-energy particles create high-density plasma near the gate, leading to an irreversible transistor breakdown.
Conclusion
Space radiation poses significant risks to electronic devices, affecting their longevity and functionality. Understanding and mitigating these effects is crucial for spacecraft design and reliability.
References
- ALTERA - Understanding Single Event Functional Interrupts in FPGA Designs
- Kenneth A. LaBel - Single Event Effects (SEEs) Specification Approach
- Mengfei Yang et al. - Fault-Tolerance Techniques for Spacecraft Control Computers
- Peter Fortescue et al. - Spacecraft Systems Engineering (4th Edition)
- Raoul Velazco et al. - Radiation Effects on Embedded Systems