Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, Japan.
PLoS One. 2022 Nov 3;17(11):e0276364. doi: 10.1371/journal.pone.0276364. eCollection 2022.
The displacement damage dose (DDD) is a common index used to predict the life of semiconductor devices employed in space-based environments where they will be exposed to radiation. The DDD is commonly estimated from the non-ionizing energy loss based on the Norgett-Robinson-Torrens (NRT) model, although a new definition for a so-called effective DDD considers the molecular dynamic (MD) simulation with the amorphization in semiconductors. The present work developed a new model for calculating the conventional and effective DDD values for silicon carbide (SiC), indium arsenide (InAs), gallium arsenide (GaAs) and gallium nitride (GaN) semiconductors. This model was obtained by extending the displacement per atom tally implemented in the particle and heavy ion transport code system (PHITS). This new approach suggests that the effective DDD is higher than the conventional DDD for arsenic-based compounds due to the amorphization resulting from direct impacts, while this relationship is reversed for SiC because of recombination defects. In the case of SiC and GaN exposed to protons, the effective DDD/conventional DDD ratio decreases with proton energy. In contrast, for InAs and GaAs, this ratio increases to greater than 1 at proton energies up to 100 MeV and plateaus because the defect production efficiency, which is the ratio of the number of stable displacements at the end of collision cascade simulated by MD simulations to the number of defects calculated by NRT model, does not increase at damage energy values above 20 keV. The practical application of this model was demonstrated by calculating the effective DDD values for semiconductors sandwiched between a thin glass cover and an aluminum plate in a low-Earth orbit. The results indicated that the effective DDD could be dramatically reduced by increasing the glass cover thickness to 200 μm, thus confirming the importance of shielding semiconductor devices used in space. This improved PHITS technique is expected to assist in the design of semiconductors by allowing the effective DDD values for various semiconductors having complex geometries to be predicted in cosmic ray environments.
位移损伤剂量（DDD）是一种常用的指标，用于预测在空间环境中使用的半导体器件的寿命，因为它们将暴露在辐射下。DDD 通常根据非电离能量损失基于 Norgett-Robinson-Torrens（NRT）模型来估算，尽管对于所谓的有效 DDD 有一个新的定义，考虑了半导体中的分子动力学（MD）模拟和非晶化。本工作为碳化硅（SiC）、砷化铟（InAs）、砷化镓（GaAs）和氮化镓（GaN）半导体开发了一种新的计算常规和有效 DDD 值的模型。该模型是通过扩展在粒子和重离子输运代码系统（PHITS）中实现的每个原子的位移计数获得的。这种新方法表明，由于直接影响导致的非晶化，基于砷的化合物的有效 DDD 高于常规 DDD，而对于 SiC，由于重组缺陷，这种关系相反。对于暴露于质子的 SiC 和 GaN，有效 DDD/常规 DDD 比值随质子能量的降低而降低。相比之下，对于 InAs 和 GaAs，当质子能量高达 100 MeV 时，该比值增加到 1 以上，并趋于平稳，因为缺陷产生效率（即由 MD 模拟模拟的碰撞级联结束时稳定位移的数量与 NRT 模型计算的缺陷数量的比值）在损伤能量值高于 20 keV 时不会增加。通过计算在低地球轨道中夹在薄玻璃盖和铝板之间的半导体的有效 DDD 值，证明了该模型的实际应用。结果表明，通过将玻璃盖厚度增加到 200 µm，可以显著降低有效 DDD，从而证实了在空间中使用的半导体器件屏蔽的重要性。这种改进的 PHITS 技术有望通过预测具有复杂几何形状的各种半导体在宇宙射线环境中的有效 DDD 值，来辅助半导体的设计。
