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arXiv 1601.03802cond-mat.mtrl-sci
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热退火后Sn注入a-SiO2基质中Sn的损失效应:XPS、PL和DFT的联合研究

Sn-loss effect in a Sn-implanted a-SiO2 host-matrix after thermal annealing: A combined XPS, PL, and DFT study

D. A. Zatsepin, A. F. Zatsepin, D. W. Boukhvalov, E. Z. Kurmaev, N. V. Gavrilov

摘要:

无定形a-SiO2主体基质用Sn离子注入,在环境空气中在900 °C下进行和不进行后热回火1小时。采用X射线光电子能谱学分析(XPS核心能级、XPS价带映射)、光致发光(PL)探测和密度泛函计算(DFT)对这些样品进行详细的电子结构表征。实验确定Sn嵌入a-SiO2基质的过程遵循两种不同的趋势:在a-SiO2:Sn中Sn 4 + -> Si 4+取代(没有回火),以及在a-SiO2:Sn中Sn金属簇集作为杂质(900 ℃,1小时)。这两种趋势进行了建模,使用计算的形成能和偏态密度(PDOS)以及价带(VB)模拟,这产生的证据表明,替代缺陷产生的帮助下发生离子注入刺激易位的主机原子从其化学计量位置的间隙空隙。所获得的实验和理论数据在a-SiO2:Sn(900 °C,1小时)中由于热诱导的电子主体结构重新排列而报告的Sn损失效应方面一致,这表现为主体原子向后移位到化学计量位置和Sn-金属簇的后形成。

英文摘要:

Amorphous a-SiO2 host-matrices were implanted with Sn-ions with and without posterior thermal tempering at 900 °C for 1 hour in ambient air. X-ray photoelectron spectroscopy analysis (XPS core-levels, XPS valence band mapping), photoluminescence (PL) probing, and density functional calculations (DFT) were employed to enable a detailed electronic structure characterization of these samples. It was experimentally established that the process of Sn-embedding into the a-SiO2 host occurs following two dissimilar trends: the Sn4+ -> Si4+ substitution in a-SiO2:Sn (without tempering), and Sn-metal clustering as interstitials in a-SiO2:Sn (900 °C, 1 hour). Both trends were modeled using calculated formation energies and partial densities of states (PDOS) as well as valence band (VB) simulations, which yielded evidence that substitutional defect generation occurs with the help of ion-implantation stimulated translocation of the host-atoms from their stoichiometric positions to the interstitial void. Experimental and theoretical data obtained coincide in terms of the reported Sn-loss effect in a-SiO2:Sn (900 °C, 1 hour) due to thermally-induced electronic host-structure re-arraignment, which manifests as backward host-atoms translocation into stoichiometric positions and the posterior formation of Sn-metal clusters.

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