Atomistic nitriding processes of titanium thin films due to nitrogen-implantation
Atomistic nitriding processes of titanium thin films due to nitrogen-implantation
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DOI：
10.1016/j.apsusc.2008.03.191
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发表时间：
2008-09
影响因子：
6.7
通讯作者：
Y. Kasukabe;S. Nishida;S. Yamamoto;M. Yoshikawa;Y. Fujino
中科院分区：
文献类型：
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作者：
Y. Kasukabe;S. Nishida;S. Yamamoto;M. Yoshikawa;Y. Fujino
室温下，将62 keV的氮离子（N2+）注入沉积态Ti膜中，主要由（110）取向的TiHx和（03·5）取向的hcp-Ti组成，分别外延形成（110）取向和（001）取向的TiNy。电子能量损失谱实验表明，在N离子注入初期，TiHx中氢的释放导致等离子体激发的能量损失峰向低能侧移动。另一方面，由于等离子体激元激发氮化的hcp-Ti的能量损失峰逐渐转移到更高的能量侧随着剂量的增加。通过氮侵入hcp-Ti中具有较大空间和较低电子密度的八面体位置，通过形成强的Ti-N键（包括π型共价键）促进hcp-Ti的（00·1）面向01 <$0方向移动，并通过削弱Ti-Ti键，诱导Ti亚晶格的hcp-fcc转变。此外，在转变的fcc-Ti亚晶格中，正方形原子排列的遗传和N原子向其他相邻O位的移动是导致TiNy外延生长的原因。借助分子轨道计算，讨论了TiNy外延生长的原子过程。
Nitrogen ions (N2+) with 62keV were implanted into the as-deposited Ti film composed of mainly (110)-oriented TiHxand (03·5)-oriented hcp-Ti at room temperature, which results in the epitaxial formation of (110)-oriented and (001)-oriented TiNy, respectively. The electron energy loss spectroscopy experiments elucidate that in the early N-implanting stage the release of hydrogen constituting TiHxgives rise to the shift of the loss peak due to plasmon excitation to lower loss energy side. On the other hand, the energy loss peaks due to plasmon excitation for nitriding of hcp-Ti gradually shifted to higher energy side with increasing dose. Through the N-invasion into the octahedral sites of hcp-Ti with larger space and lower electron density, the hcp–fcc transformation of Ti sublattices is induced by the shift of the (00·1)-plane in the 01⋅0 direction of hcp-Ti promoted by the forming of the strong Ti–N bonds including the π-type covalent bonds, and by the weakening of the Ti–Ti bonds. Furthermore, the inheritance of square atomic arrangement and the movement of the N atom to other neighboring O-site in the transformed fcc-Ti sublattice are responsible for the epitaxial growth of TiNy. The atomistic processes of the epitaxial growth of TiNyare discussed with the aid of the molecular orbital calculations.