1.Research Background
New-generation spacecraft (such as electric propulsion satellites) need to adopt 1200V high-voltage fast recovery diodes to improve efficiency and reduce weight. For instance, NASA research shows that a 300V solar power system weighs 2457kg less than a 120V system, and the trend towards high-voltageization is obvious. However, the space radiation environment (single particle effect, ionizing total dose effect, etc.) poses a threat to the reliability of the devices, especially the single particle burnout (SEB) which may cause failure. Therefore, it is crucial to study the radiation resistance of high-voltage fast recovery diodes.
2.Experimental Method
2.1 Particle Selection and Irradiation Rate
In China, the HIRFL (LET > 95 MeV·cm²/mg) cyclotron and the HI-13 (LET ≤ 37.2 MeV·cm²/mg) tandem electrostatic accelerator are used to simulate space radiation. The test irradiation rate is usually 1 to 10⁴/(cm²·s), and high irradiation rate is used to accelerate the SEB assessment.
2.2 Single Particle Effect Detection System
- Real-time Monitoring: Detects cathode-anode leakage current (at the nA level), using a high-precision operational amplifier circuit to convert tiny current signals.
- Remote Control: Controls the reverse voltage (VR) via a PC, automatically collects data, ensuring the safety of the test.
2.3 Sample Preparation
Traditional glass passivated packaged diodes cannot be directly tested due to range limitations. Therefore, an equivalent sample preparation method is adopted:
- Glass internal passivation process: Protect the chip structure and switch to metal packaging (such as TO type).
- Test procedure: Monitor the leakage current (IR). If the IR suddenly increases or the device conducts, it is determined as SEB. The process stops when the dosage reaches 1×10⁷/cm² or when one SEB occurs.
3.Test Results and Analysis
Tests were conducted on 1200V fast recovery diodes from Companies A, B, and C:
- Company A: When VR = 820V, the LET threshold for anti-SEB was > 81.35 MeV·cm²/mg.
- Company B: When VR = 940V, the LET threshold is greater than 81.35 MeV·cm²/mg.
- Company C: When VR = 840V, the LET threshold is greater than 79.24 MeV·cm²/mg; the safe voltage range is 840 to 960V.
Failure Mechanism
SEB may occur in the terminal structure or the active region:
- Terminal region: The impingement of high-energy particles causes a sudden increase in transient current, and local overheating leads to breakdown.
- Active region: Under the electric field, electron-hole pairs form a large current, triggering avalanche breakdown and thermal failure.
Conclusion and Outlook
This study has established an evaluation method for single-particle effects of high-voltage fast recovery diodes, providing data support for aerospace applications. In the future, the design of device reinforcement needs to be further optimized to enhance the anti-SEB capability.The above information has been compiled by SHYSEMI. We hope it will be helpful to you.