Monolayer Doping via Phosphonic Acid Grafting on Silicon: Microscopic Insight from Infrared Spectroscopy and Density Functional Theory Calculations
Monolayer Doping via Phosphonic Acid Grafting on Silicon: Microscopic Insight from Infrared Spectroscopy and Density Functional Theory Calculations
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DOI：
10.1002/adfm.201202808
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发表时间：
2013-07-19
影响因子：
19
通讯作者：
Thissen, Peter
中科院分区：
文献类型：
--
作者：
Longo, Roberto C.;Cho, Kyeongjae;Thissen, Peter
单层掺杂（MLD）是用于产生超浅结（USJ）的有前途的技术。在这里，提出了一种新的自组装单分子层（SAM）接枝技术，通过一个单一的氧原子能够MLD。因此，这种方法可以使用简单形式的烷基膦酸，并在掺杂过程中完全避免碳污染。本文采用密度泛函理论（DFT）研究了烷基膦酸分子如何通过一步化学反应接枝到H-端Si（111）上。由于空间位阻的作用，烷基膦酸的最大覆盖率在2/3处。通过原位红外光谱和DFT计算进一步证明，烷基膦酸（例如十八烷基膦酸（ODPA））的弱连接是P-C键，其中典型的碳配体在500 ℃左右释放。最后，在碳配体释放后，不饱和电子构型是磷开始MLD过程的驱动力。
Monolayer doping (MLD) is a promising technique for creating ultra shallow junctions (USJs). Here, a novel self assembled monolayer (SAM) grafting technique is proposed through a single oxygen atom capable of MLD. Consequently, this approach can use simple forms of alkylphosphonic acids and avoid carbon contamination altogether during the doping process. In this paper, density functional theory (DFT) is used to explore the way how alkylphosphonic acid molecules can in just one chemical step be grafted on H-terminated Si(111). A maximum coverage of alkylphosphonic acids is found at 2/3 due to steric constrain forces. It is further demonstrated by means of in situ infrared spectroscopy and DFT calculations that the weak link of an alkylphosphonic acid, such as octadecylphosphonic acid (ODPA), is the P-C bond, with typical release of the carbon ligand around 500 degrees C. Finally, after release of the carbon ligand, an unsaturated electron configuration is driving force for the phosphorous to start the MLD process.