Ferroelectricity in undoped hafnium oxide
Ferroelectricity in undoped hafnium oxide
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DOI：
10.1063/1.4922272
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发表时间：
2015-06-08
影响因子：
4
通讯作者：
Mueller, Johannes
中科院分区：
文献类型：
--
作者：
Polakowski, Patrick;Mueller, Johannes
我们报告的铁电特性的观察在未掺杂的氧化铪薄膜的厚度范围为4-20 nm。使用原子层沉积（ALD）制造未掺杂的膜，并将其嵌入基于氮化钛的金属-绝缘体-金属（MIM）电容器中用于电评估。收集了纯氧化铪中铁电相出现的结构和电学证据，这些证据与氮化钛电极形成过程中施加的膜厚度和热预算有关。使用掠入射X-射线衍射（GIXRD）分析，我们观察到的正交晶系，潜在的，铁电相有利于降低厚度/晶粒尺寸和低于结晶温度的氮化钛电极形成的单斜相分数的增强抑制。使用极化测量证实了铁电性的电存在。对于纯氧化物，测量到高达10 μ C cm（-2）的回复极化P-r以及1.6 × 10（5）次循环的读/写耐久性。这里报道的实验结果有力地支持了氧化铪中铁电相的本征性质，并将其适用性扩展到掺杂系统之外。(C)2015 AIP Publishing LLC.
We report the observation of ferroelectric characteristics in undoped hafnium oxide thin films in a thickness range of 4-20 nm. The undoped films were fabricated using atomic layer deposition (ALD) and embedded into titanium nitride based metal-insulator-metal (MIM) capacitors for electrical evaluation. Structural as well as electrical evidence for the appearance of a ferroelectric phase in pure hafnium oxide was collected with respect to film thickness and thermal budget applied during titanium nitride electrode formation. Using grazing incidence X-Ray diffraction (GIXRD) analysis, we observed an enhanced suppression of the monoclinic phase fraction in favor of an orthorhombic, potentially, ferroelectric phase with decreasing thickness/grain size and for a titanium nitride electrode formation below crystallization temperature. The electrical presence of ferroelectricity was confirmed using polarization measurements. A remanent polarization P-r of up to 10 mu C cm(-2) as well as a read/write endurance of 1.6 x 10(5) cycles was measured for the pure oxide. The experimental results reported here strongly support the intrinsic nature of the ferroelectric phase in hafnium oxide and expand its applicability beyond the doped systems. (C) 2015 AIP Publishing LLC.