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Wide-gap semiconductor SiC is generally considered as a superior candidate for high-radiation applications, due to its higher displacement energy for both Si and C lattice atoms. In this work, we find that the current gain ($\beta $) of 4H-SiC bipolar junction transistors (BJTs) can severely deteriorate after neutron irradiation. Deep-level transient spectroscopy (DLTS) reveals that two major carrier-killer centers, Z1/2 and EH6/7, were produced in neutron-irradiated devices. Surprisingly, we find that the shallow Z1/2 center can play a dominant role over the deep EH6/7 defects in carrier recombination under high-injection conditions, which contributes to the unusual smaller hole capture cross section than that of the electron one, as indicated by the first-principles calculations. Finally, technology computer aided design (TCAD) simulation confirms that the enhanced carrier recombination from the Z1/2 centers is responsible for the degraded performance of SiC BJTs after irradiation. Our findings not only provide a deep insight into the underlying physics for displacement damage in SiC BJTs, but also are of interest for technological applications field related to high-energy particle irradiation or implantation. [ABSTRACT FROM AUTHOR]

The impact of electrical stress on the defect generation behaviors in thin GeO2/n-Ge gate stacks has been investigated through the measurement of the time-dependent dielectric breakdown (TDDB) and the stress-induced leakage current (SILC) characteristics. A multiple-spot breakdown (BD) event is confirmed, as well as a larger SILC generation probability compared with that in SiO2/Si structures. It is found that the slow trap generation is dominant by the amount of injected electron fluence (Qinj), and the fix charge generation is attributed to both Qinj and GeO2 thickness. [ABSTRACT FROM AUTHOR]

Perovskite ferroelectrics have high endurance to radiation. In order to understand the mechanism at the atomic level, molecular dynamics simulation is applied to investigate the process of defects generation and displacement cascades in BaTiO3 crystal. The calculated average threshold displacement energy of O, Ba and Ti atom is 53 eV, 70 eV, and 119 eV, respectively, so the number of O defects is larger than that of Ba and Ti defects. Furthermore, the simulations show that the initial movement direction of the primary knock-on atom (PKA) has significant influence on the number of defects because of different collision type (glancing collisions or direct knocks), and the number of Frenkel defects does not simply increase with increasing PKA energy due to the annealing effect. This investigation of the collision cascades is helpful to understand the radiation damage in BaTiO3 crystal and may offer useful guidelines to the design and applications for the practical devices. [ABSTRACT FROM AUTHOR]

Abstract: The effect of constant voltage stress (CVS) on Pt/La2O3/n-Ge MOS devices biased at accumulation is investigated and reported. It is found that the stress induced leakage current (SILC) initially increases due to electron charge trapping on pre-existing bulk oxide defects. After 10s approximately, a clear decay of SILC commences which follows a t − n power law, with n lying between 0.56 and 0.75. This decay of SILC is not changed or reversed when the stressing voltage stops for short time intervals. The effect is attributed to the creation of new positively charged defects in the oxide because of the applied stressing voltage, while other mechanism such as dielectric relaxation proposed in the past is proved insufficient to explain the experimental data. Also high frequency capacitance vs. gate voltage (C–Vg ) curves measured under different CVS conditions divulge the creation of defects and charge trapping characteristics of La2O3 preciously. At low CVS exemplify the generation positively charged defects, however at higher CVS charge trapping obeys a model that was previously proposed and is a continuous distribution of traps. [Copyright &y& Elsevier]