Quantifying atom-scale dopant movement and electrical activation in Si:P monolayers
Xiqiao Wang1, Joseph A Hagmann, Pradeep Namboodiri
1National Institute of Standards and Technology, 100 Bureau Dr., Gaithersburg, Maryland 20899, USA. richard.silver@nist.gov.
Nanoscale
|February 21, 2018
Summary
Advanced techniques precisely pattern phosphorus-doped silicon monolayers for quantum computing. A new method using locking layers controls dopant movement, enabling atomic-scale precision in 2-D superlattices.
Area of Science:
- Semiconductor Physics
- Quantum Computing Materials
Background:
- Advanced hydrogen lithography enables precise patterning of phosphorus-doped silicon (Si:P) monolayers for quantum computing and 2D superlattices.
- Challenges include dopant segregation, diffusion, and defect formation during overgrowth, impacting dopant placement accuracy.
Purpose of the Study:
- Develop a method to monitor and control atomic-scale dopant movement in Si:P monolayers.
- Investigate the impact of locking layers (LLs) on dopant confinement and electrical activation.
Main Methods:
- Combined dopant segregation/diffusion models with sputter profiling simulations.
- Utilized room-temperature grown locking layers (LLs) with varying growth rates and thicknesses.
- Explored rapid thermal annealing and surface accumulation effects.
Main Results:
- Increasing LL growth rate is more effective than increasing LL thickness for suppressing dopant movement.
- Achieved dopant segregation lengths below a single Si lattice constant at room temperature.
- Demonstrated sharp dopant confinement and high electrical quality using high LL growth rate and low-temperature annealing.
Conclusions:
- Developed a novel method for atomic-scale dopant movement control in 2D Si:P systems.
- This technique is crucial for 2D fabrication requiring precise dopant placement.
- Enables suppression, quantification, and prediction of single dopant movement.
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