Physical mechanism determining Ge p- and n-MOSFETs mobility in high Ns region and mobility improvement by atomically flat GeOx/Ge interfaces
Physical mechanism determining Ge p- and n-MOSFETs mobility in high Ns region and mobility improvement by atomically flat GeOx/Ge interfaces
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DOI：
10.1109/iedm.2012.6479051
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发表时间：
2012-12
期刊：
影响因子：
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通讯作者：
Rui Zhang;Po-Chin Huang;Ju-Chin Lin;M. Takenaka;S. Takagi
中科院分区：
文献类型：
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作者：
Rui Zhang;Po-Chin Huang;Ju-Chin Lin;M. Takenaka;S. Takagi
对不同衬底取向和GeOx/Ge界面质量的Ge p型和n型MOSFET进行了霍尔测量。发现Ge MOSFET在高表面载流子浓度（Ns）或高法向电场下有效迁移率的显著降低部分归因于Ge的价带和导带内大量的界面态导致的Ns损失。GeOx/Ge界面粗糙度是限制高Ns迁移率的另一个原因。结果表明，室温等离子体后氧化可以实现GeOx/Ge界面原子级平坦的Al_2O_3/GeOx/Ge栅叠层。具有这些界面的Ge MOSFET提供了创纪录的高有效空穴和电子迁移率，其克服了低和高Ns区中的Si通用迁移率。
Hall measurements have been carried out for the Ge p-and n-MOSFETs with different substrate orientations and GeOx/Ge interface qualities. It is found that the significant reduction of effective mobility in high surface carrier concentration (Ns) or high normal field in Ge MOSFETs is attributed partly to the Ns loss due to large amounts of interface states inside the valence and conduction bands of Ge. The GeOx/Ge interface roughness is another reason limiting the high Ns mobility. It has been revealed that room temperature plasma post oxidation can realize Al2O3/GeOx/Ge gate stacks with atomically-flat GeOx/Ge interfaces. Ge MOSFETs with these interfaces have provided record high effective hole and electron mobility, which overcome the Si universal mobility in both low and high Ns regions.