Identification and thermodynamic mechanism of the phase transition in hafnium nitride films

	Identification and thermodynamic mechanism of the phase transition in hafnium nitride films
	Gu, Z. Q.; C. Q. Hu; H. H. Huang; S. Zhang; X. F. Fan; X. Y. Wang and W. T. Zheng
	2015
发表期刊	Acta Materialia
卷号	90 页码:59-68
摘要	A stoichiometry-driven phase transition from rocksalt to "nitrogen-rich" structure exists in group-IVB transition metal nitride films. As this phase transition is critical in controlling the film properties it has attracted numerous studies. However, researchers are still divided with regard to the structural identity of this "nitrogen-rich" phase, not to mention detailed exploration of the phase transition mechanisms. In this study, we confirmed that the "nitrogen-rich" phase in hafnium nitride (HfNx) films had a cubic Th3P4 structure of space group symmetry of I-43d (220), namely c-Hf3N4. The confirmation was obtained by combining the first-principle calculations with a series of experiments: Selected Area Electron Diffraction, High Resolution Transmission Electron Microscopy, Raman, Gracing Incident X-ray Diffraction and X-ray Photoelectron Spectroscopy. The mechanisms of the phase transition were elucidated through calculations on enthalpy of formation (EOF). The experimental results agree well with the theoretical calculations. We conclude that with increasing nitrogen, phase transition takes place from rocksalt (delta-HfN) to c-Hf3N4 through three stages of structural evolution: (delta-HfN (containing Hf vacancies) -> mixture of (delta-HfN + c-Hf3N4) -> c-Hf3N4. The driving force of the phase transition is energy minimization. The three stages of structural evolution are explained by comparing the EOF of the (delta-HfN and c-Hf3N4 phases. As the phase transition takes place, the hafnium nitride film morphs from a conductive and opaque metal into an insulating and transparent semiconductor. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
收录类别	SCI ; EI
文献类型	期刊论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/55255
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	Gu, Z. Q.,C. Q. Hu,H. H. Huang,et al. Identification and thermodynamic mechanism of the phase transition in hafnium nitride films[J]. Acta Materialia,2015,90:59-68.
APA	Gu, Z. Q.,C. Q. Hu,H. H. Huang,S. Zhang,X. F. Fan,&X. Y. Wang and W. T. Zheng.(2015).Identification and thermodynamic mechanism of the phase transition in hafnium nitride films.Acta Materialia,90,59-68.
MLA	Gu, Z. Q.,et al."Identification and thermodynamic mechanism of the phase transition in hafnium nitride films".Acta Materialia 90(2015):59-68.

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