Ge interface engineering using ultra-thin La2O3 and Y2O3 films: A study into the effect of deposition temperature
Ge interface engineering using ultra-thin La2O3 and Y2O3 films: A study into the effect of deposition temperature
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DOI：
10.1063/1.4868091
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发表时间：
2014-03-21
影响因子：
3.2
通讯作者：
Dimoulas, A.
中科院分区：
文献类型：
--
作者：
Mitrovic, I. Z.;Althobaiti, M.;Dimoulas, A.
本文研究了超薄La_2O_3/Ge和Y_2O_3/Ge栅叠层的最佳淀积温度，目的是调整界面层以有效钝化Ge界面。两种镧系氧化物（La 2 O3和Y2 O3）之间的详细比较中使用中能离子散射，真空紫外可变角光谱椭圆偏振仪（VUV-VASE），X射线光电子能谱，和X射线衍射的能带排列，界面特征，和反应性锗。已经发现La 2 O3比Y2 O3对Ge更有反应性，在所研究的所有沉积温度（在44摄氏度至400摄氏度的范围内）下，在界面处形成LaGeOx和Ge低价氧化物。相比之下，在400摄氏度下沉积的Y2 O3/Ge允许在界面处形成超薄GeO 2层，其可以在高于525摄氏度的温度下退火期间消除，留下原始的YGeOx/Ge界面。在较低温度下沉积的Y2 O3/Ge栅叠层显示出与能量为1.1eV的Urbach尾拟合的子带隙吸收特征。后者与界面处的亚化学计量的氧化锗层相关。Y2 O3/Ge叠层的光学带隙已被估计为5.7 +/- 0.1 eV的Tauc-Lorentz模型的VUV-VASE实验数据。对于最佳沉积温度（400摄氏度）时，Y2 O3/Ge叠层表现出更高的导带偏移（>2.3 eV），比La 2 O3/Ge（类似于2 eV），具有更大的带隙（约0.3eV），无锗低价氧化物界面，并且漏电流（类似于1V时的10（-7）A/cm（2））比相应的La 2 O3/Ge叠层低五个数量级。我们的研究有力地指出了Y2 O3/Ge系统在锗界面工程中的优越性，以实现高性能的Ge互补金属氧化物半导体技术。(C)2014 AIP出版有限责任公司。
A study into the optimal deposition temperature for ultra-thin La2O3/Ge and Y2O3/Ge gate stacks has been conducted in this paper with the aim to tailor the interfacial layer for effective passivation of the Ge interface. A detailed comparison between the two lanthanide oxides (La2O3 and Y2O3) in terms of band line-up, interfacial features, and reactivity to Ge using medium energy ion scattering, vacuum ultra-violet variable angle spectroscopic ellipsometry (VUV-VASE), X-ray photoelectron spectroscopy, and X-ray diffraction is shown. La2O3 has been found to be more reactive to Ge than Y2O3, forming LaGeOx and a Ge sub-oxide at the interface for all deposition temperature studied, in the range from 44 degrees C to 400 degrees C. In contrast, Y2O3/Ge deposited at 400 degrees C allows for an ultra-thin GeO2 layer at the interface, which can be eliminated during annealing at temperatures higher than 525 degrees C leaving a pristine YGeOx/Ge interface. The Y2O3/Ge gate stack deposited at lower temperature shows a sub-band gap absorption feature fitted to an Urbach tail of energy 1.1 eV. The latter correlates to a sub-stoichiometric germanium oxide layer at the interface. The optical band gap for the Y2O3/Ge stacks has been estimated to be 5.7 +/- 0.1 eV from Tauc-Lorentz modelling of VUV-VASE experimental data. For the optimal deposition temperature (400 degrees C), the Y2O3/Ge stack exhibits a higher conduction band offset (>2.3 eV) than the La2O3/Ge (similar to 2 eV), has a larger band gap (by about 0.3 eV), a germanium sub-oxide free interface, and leakage current (similar to 10(-7) A/cm(2) at 1V) five orders of magnitude lower than the respective La2O3/Ge stack. Our study strongly points to the superiority of the Y2O3/Ge system for germanium interface engineering to achieve high performance Ge Complementary Metal Oxide Semiconductor technology. (C) 2014 AIP Publishing LLC.