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Research Team from SJTU Indicates New Direction of Self-assembled Molecular Monolayer

January 10, 2018      Author: Zhou Weirong

Recently, a research team led by Prof. Dan Yaping from UM-SJTU Joint Institute released the latest research result "Deep level transient spectroscopic investigation of phosphorus-doped silicon by self-assembled molecular monolayers" in the internationally renowned academic journal the Nature Communications. The paper describes the team's discovery that self-assembled monolayer doping introduces carbon defects in the silicon substrate, thereby reducing the electrical activation of phosphorus in silicon. The study points out the research direction of self-assembled monolayers doping technology, laying the foundation for the defect-free monolayer doping technology. The corresponding author of this paper is Prof. Dan Yaping. Doctoral student Gao Xuejiao and postdoctoral student Guan Bin are joint first authors.

It is known that self-assembled molecular monolayer doping technique has the advantages of forming ultra-shallow junctions and introducing minimal defects in semiconductors. In this paper, we report however the formation of carbon-related defects in the molecular monolayer-doped silicon as detected by deep-level transient spectroscopy and low-temperature Hall measurements. The molecular monolayer doping process is performed by modifying silicon substrate with phosphorus-containing molecules and annealing at high temperature. The subsequent rapid thermal annealing drives phosphorus dopants along with carbon contaminants into the silicon substrate, resulting in a dramatic decrease of sheet resistance for the intrinsic silicon substrate. Low-temperature Hall measurements and secondary ion mass spectrometry indicate that phosphorus is the only electrically active dopant after the molecular monolayer doping. However, during this process, at least 20% of the phosphorus dopants are electrically deactivated. The deep-level transient spectroscopy shows that carbon-related defects are responsible for such deactivation.


Prof. Dan Yaping is currently a special research fellow and associate professor from UM-SJTU Joint Institute. Prof. Dan graduated from Xi'an Jiao Tong University in 1999 as Bachelor Degree, graduated from Tsinghua University in 2002 as Master Degree, and received Doctoral degree from University of Pennsylvania in 2008. After graduate with a doctorate, he worked as a postdoctoral fellow at Harvard University. In 2012, he joined the Michigan Institute of SJTU. In the same year, he was selected as "Young Thousands of People Program" by the Central Organization Department. Professor Dan Yaping focuses his research on all silicon-based photoelectronics and monatomic electronics, providing key solutions for future advanced integrated circuits and quantum computer technologies.