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首页> 外文期刊>Journal of Applied Physics >Characterization of sputtering products during graphite exposure to deuterium ions by molecular dynamics
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Characterization of sputtering products during graphite exposure to deuterium ions by molecular dynamics

机译：通过分子动力学表征石墨暴露于氘离子中的溅射产物

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摘要

We study sputtering by 100 eV deuterium irradiation on deuterated amorphous carbon layers at 300 K using molecular dynamics (MD) simulations. Two main results are reported here. First, a special mechanism for carbon release-additional to and distinct from the standard definitions for physical and chemical sputtering of carbon by hydrogen isotopes-has been identified and quantified. This process, here termed ion induced release of unsaturated hydrocarbons (IRUH's), is primarily due to a recently identified atomic collision process where momentum from an impacting particle is transferred approximately perpendicular to the C-C bond, severing it. For the prescribed conditions, the IRUH yield has been found to be comparable to that of standard physical and chemical sputtering, the former being also consistently and simultaneously calculated here. IRUH release of single C atoms does not involve any hydrogenic chemistry and is therefore properly considered to be a distinct and additive type of physical sputtering to that of standard physical sputtering. For 100 eV D~+ the single C yields of the two physical sputtering mechanisms have been found to be approximately equal. IRUH release of carbon is directly from the surface region of the solid and is separate from, and additional to, standard chemical sputtering (not included in these MD calculations), which typically produces saturated hydrocarbons such as CD_4, from regions extending over the stopping depth of the deuteron in the solid. IRUH is evidently included in experimental measurements of total sputtering yield, e.g., by weight loss. The average energy of IRUH carbon products is about 1 eV and the angular distribution is consistent with a cosine distribution. Second, it is found that for the standard physically sputtered single C atoms the energy distribution is roughly consistent with the widely used Thompson distribution-this despite the fact that the assumptions on which the Thompson distribution is based are not satisfied for 100 eV D on C. The angular distribution of the standard physically sputtered single C atoms is also found to be consistent with the usually assumed cosine distribution.
机译：我们使用分子动力学（MD）模拟研究了100 eV氘辐射在300 K下对氘代无定形碳层的溅射。这里报告了两个主要结果。首先，已经确定并定量了一种特殊的碳释放机理，该机理是氢同位素对碳进行物理和化学溅射的标准定义的补充，并与之不同。这个过程，这里称为离子诱导释放不饱和烃（IRUH），主要是由于最近发现的原子碰撞过程，其中来自撞击粒子的动量大约垂直于C-C键转移而被切断。对于规定的条件，已发现IRUH的产量可与标准物理和化学溅射的产量相媲美，前者在此处也是一致且同时计算的。 IRUH释放的单个C原子不涉及任何氢化学，因此可以适当地认为它是物理溅射与标准物理溅射不同的附加类型。对于100 eV D〜+，已经发现两种物理溅射机理的单C收率大致相等。 IRUH释放的碳直接来自固体的表面区域，并且与标准化学溅射（这些MD计算中不包括）分开进行，此外，该化学溅射通常会从超过停止深度的区域中产生饱和烃，例如CD_4。氘核在固体中。 IRUH显然包括在总溅射产率的实验测量中，例如通过重量损失。 IRUH碳产品的平均能量约为1 eV，角度分布与余弦分布一致。其次，发现对于标准物理溅射的单个C原子，其能量分布与广泛使用的Thompson分布大致一致-尽管事实是，对于C上100 eV D而言，Thompson分布所基于的假设都无法满足还发现标准物理溅射的单个C原子的角分布与通常假定的余弦分布一致。

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