TCAD Simulation of the Single Event Effects in Normally-off GaN Transistors after Heavy Ion Radiation

Abstract

Electrical behavior of commercial off-the-shelf normally-off GaN power transistors under heavy ion irradiation is presented based on technology computer aided design numerical simulation in order to better understand the mechanism of single event effects (SEEs) in these devices. First, the worst case has been defined from the single event transient mechanism. Then, the decrease in the electric field observed after irradiation and the traps effect have been addressed. Finally, possible mechanisms of SEE in these devices under heavy ion are proposed.

TCAD simulation of the single event effects in normally-off GaN transistors after heavy ion radiation

“…Fig. 5 confirms that the amplitude values of the drain current can be multiplied by a factor 6 when increasing the drain-source bias voltage for the same charge deposited by the heavy ion [27]. Fig.…”

“…5 confirms that the amplitude values can be multiplied by increasing the drain-source bias voltage for the same charge deposited by the heavy ion. Since the ionization coefficients and detrapping are exponentially related to the electric field via Poisson's equations, the rise in the polarization increases the detrapping and the generation of electron-hole pairs, increasing the hole current in the gate, leads to more charge enhancement [27]. This is similar to the direct characteristic I D (V DS ): the saturation drain current increases with the increase in gate bias (V GS ).…”

“…For V DS less than 200 V, the impact ionization mechanism has no effect. Furthermore, the very high current densities and conductivity of the GaN generated by the avalanche is assumed not to be supported by its limited thermal capacity and thermal conductivity (related to the Si substrate limitation); as a consequence, this increases the risk of thermal runaway [27].…”

“…Several studies of SEGR in power MOSFETs have shown that the gate leakage current resulting from the ion impact has been increasing rapidly with the exposure time under the beam. This increase can lead to the breakdown of the gate oxide (SiO 2 ) in most cases [27].…”

TSV Technology and High-Energy Heavy Ions Radiation Impact Review

“…This study will help provide a basis for establishing a complete TPA (two-photon absorption) and heavy ion correlation method in SiGe HBT technology. The SEE of GaN (gallium nitride) transistors after heavy-ion radiation using TCAD software, proposed by M. Zerarka et al [111], shows that the self-polarization of the gate caused by the hole current originating from the ion beam leads to a momentary turn-on of the device. The worst result occurred at 200 V commercial normally-off GaN transistors, which are formed by the heavy ions striking FP (field plate edge) and penetrating into the 20% GaN buffer layer.…”