期刊
NANO LETTERS
卷 21, 期 21, 页码 8993-8998出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.1c02271
关键词
Quantum dots; Monolayer graphene; Bilayer graphene; Quantum chaos; STM
类别
资金
- sp2 program (KC2207) (STM imaging, device design) - Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, of the U.S. Department of Energy [DE-AC02-05CH11231]
- National Science Foundation [DMR-1753367, 1807233]
- Army Research Office [W911NF-17-1-0473]
- Elemental Strategy Initiative by the MEXT, Japan [JPMXP0112101001]
- JSPS KAKENHI [JP20H00354]
- Division Of Materials Research
- Direct For Mathematical & Physical Scien [1807233] Funding Source: National Science Foundation
The study reported the fabrication and characterization of stadium-shaped quantum dots based on graphene using a scanning tunneling microscope, attributing the absence of quantum chaos features in graphene quantum dots to Klein tunneling.
Experimental realizations of graphene-based stadium-shaped quantum dots (QDs) have been few and have been incompatible with scanned probe microscopy. Yet, the direct visualization of electronic states within these QDs is crucial for determining the existence of quantum chaos in these systems. We report the fabrication and characterization of electrostatically defined stadium-shaped QDs in heterostructure devices composed of monolayer graphene (MLG) and bilayer graphene (BLG). To realize a stadium-shaped QD, we utilized the tip of a scanning tunneling microscope to charge defects in a supporting hexagonal boron nitride flake. The stadium states visualized are consistent with tight-binding-based simulations but lack clear quantum chaos signatures. The absence of quantum chaos features in MLG-based stadium QDs is attributed to the leaky nature of the confinement potential due to Klein tunneling. In contrast, for BLG-based stadium QDs (which have stronger confinement) quantum chaos is precluded by the smooth confinement potential which reduces interference and mixing between states.
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