Molecular beam deposition of Al2O3 on p-Ge(001)/Ge0.95Sn0.05 heterostructure and impact of a Ge-cap interfacial layer
Molecular beam deposition of Al2O3 on p-Ge(001)/Ge0.95Sn0.05 heterostructure and impact of a Ge-cap interfacial layer
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DOI：
10.1063/1.3589992
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发表时间：
2011-05
影响因子：
4
通讯作者：
C. Merckling;X. Sun;Y. Shimura;A. Franquet;B. Vincent;S. Takeuchi;W. Vandervorst;O. Nakatsuka;S. Zaima;R. Loo;M. Caymax
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文献类型：
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作者：
C. Merckling;X. Sun;Y. Shimura;A. Franquet;B. Vincent;S. Takeuchi;W. Vandervorst;O. Nakatsuka;S. Zaima;R. Loo;M. Caymax
我们研究了分子束沉积Al_2O_3在Ge_（0.95）Sn_（0.05）表面上的沉积过程。我们首先通过反射高能电子衍射研究了Ge 1 −xSnx和Ge/Ge 1 −xSnx表面脱氧后的原子构型，并分别得到了c（4×2）和（2×1）表面重构。在原位沉积Al 2 O3高κ栅极电介质后，我们使用飞行时间二次离子质谱分析证明，Sn扩散是Ge 1 −xSnx/Al 2 O3栅极堆叠中高漏电流密度的起源。这种损伤可以通过在氧化物和Ge 1 −xSnx层之间插入一个5 nm厚的Ge帽来避免。最后，Ge覆盖样品上的金属氧化物半导体电容器表现出良好的电容-电压（C-V）特性，其中界面陷阱密度（Dit）在中间带隙中在1012 eV−1 cm−2的范围内，靠近价带边缘更高。
We investigated the molecular beam deposition of Al2O3 on Ge0.95Sn0.05 surface with and without an ultra thin Ge cap layer in between. We first studied the atomic configuration of both Ge1−xSnx and Ge/Ge1−xSnx surfaces after deoxidation by reflection high-energy electron diffraction and resulted, respectively, in a c(4×2) and (2×1) surface reconstructions. After in situ deposition of an Al2O3 high-κ gate dielectric we evidenced using time-of-flight secondary ion mass spectroscopy analyses that Sn diffusion was at the origin of high leakage current densities in the Ge1−xSnx/Al2O3 gate stack. This damage could be avoided by inserting a thin 5-nm-thick Ge cap between the oxide and the Ge1−xSnx layer. Finally, metal-oxide-semiconductor capacitors on the Ge capped sample showed well-behaved capacitance-voltage (C-V) characteristics with interface trap density (Dit) in the range of 1012 eV−1 cm−2 in mid gap and higher close to the valence band edge.