Irradiation capabilities of LR-0 reactor with VVER-1000 mock-up core

2019

IET Power Electronics

A comprehensive study of displacement damage and total ionisation dose effects on 4H-silicon carbide power devices is presented. Power diodes and transistors produced by different manufacturers were irradiated by high-energy particles (protons, alphas, electrons and neutrons). The influence of radiation on device characteristics was determined, the introduced radiation defects were identified, and the main degradation mechanisms were established. Results show that radiation leads to the creation of acceptor traps in the lightly doped drift regions of irradiated devices. Devices then degrade due to the removal of the carriers and the decrease in carrier mobility and lifetime. For unipolar devices, the gradual increase of the forward voltage is typical while the blocking characteristics remain nearly unchanged. In bipolar devices, high introduction rates of defects cause a sharp reduction of carrier lifetime. This results in shorter carrier diffusion lengths and subsequent loss of conductivity modulation leading to a sharp increase of the forward voltage drop. The irradiation also shifts the threshold voltage of power switches. That is critical, namely for metal-oxide-semiconductor field-effect transistors. According to the authors' study, the junction barrier Schottky diode and junction field-effect transistor (JFET) can be considered the most radiation-resistant SiC power devices.

Section: Resultsmentioning

confidence: 99%

Displacement damage and total ionisation dose effects on 4H‐SiC power devices

2019

IET Power Electronics

“…The N-epilayers were nitrogen doped in the range from 3 to 9x10 15 cm -3 . Devices were irradiated with neutrons in the LR-0 light-water nuclear reactor [4]. The 1 MeV equivalent neutron fluences calculated according to NIEL (non-ionizing energy loss) scaling in silicon were: 1.3x10 13 , 6.6x10 13 , 1.7x10 14 , and 4x10 14 cm -2 .…”

Section: Methodsmentioning

confidence: 99%

The Influence of Neutron Irradiation on Electrical Characteristics of 4H-SiC Power Devices

Záhlava

2015

MSF

Commercial 1200V and 1700V MPS diodes and 1700V vertical JFETs produced on 4H-SiC n-type epilayers were neutron irradiated with fluences up to 4x1014 cm-2 (1 MeV neutron equivalent Si). Radiation defects and their effect on carrier removal were investigated by capacitance deep-level transient spectroscopy, I-V and C-V measurement. Results show that neutron irradiation introduces different point defects giving rise to deep acceptor levels which compensate nitrogen doping of the epilayer. The carrier removal rate increases linearly with nitrogen doping. Introduced defects deteriorate ON-state characteristics of irradiated devices while their effect on blocking characteristics is negligible. The effect of neutron irradiation can be simulated by TCAD tools using a simple model accounting for introduction of one dominant deep level (Z1/Z2 centre).

“…SJEP170R550 JFET chips and packaged devices were irradiated with four different fluences of neutrons in the LR-0 light-water, pool-type research nuclear reactor in Research Centre (Czech Republic) with maximum output power 1 kW [5]. The 1 MeV neutron equivalent fluences calculated according to NIEL (non-ionizing energy loss) scaling in silicon were:…”

Section: Methodsmentioning

confidence: 99%

Effect of Neutron Irradiation on High Voltage <newline/>4H-SiC Vertical JFET Characteristics: <newline/>Characterization and Modeling

Sharma

et al. 2014

IEEE Trans. Nucl. Sci.

The effect of neutron irradiation on commercial vertical high voltage normally-OFF SiC power N-JFETs was investigated. JFETs were irradiated with 1 MeV neutron equivalent fluences up to cm . Measurement showed that fast neutrons introduce deep levels acting mostly as deep acceptor centers. These centers gradually compensate lightly doped channel and drift regions of JFETs. As a result, characteristics are deteriorated, the JFET threshold voltage gradually increases and transconductance is lowered. At fluences higher than cm , the low doped n-regions are fully compensated and transistor loses its functionality. The 2D physical model of JFET in ATLAS simulator was developed and calibrated including the neutron irradiation effects. Simulation showed a good agreement with experimental data. This confirmed that carrier removal in the channel and drift region by acceptors centers introduced by neutrons is a dominant reason of SiC JFET degradation. Index Terms-Junction field effect transistor (JFET), neutrons, radiation effects, silicon carbide (SiC).