Optical Determination of Gate--Tunable Bandgap in Bilayer Graphene
The electronic bandgap is an intrinsic property of semiconductors and insulators that largely determines their transport and optical properties. As such, it has a central role in modern device physics and technology and governs the operation of semiconductor devices such as p-n junctions, transistors, photodiodes and lasers. A tunable bandgap would be highly desirable because it would allow great flexibility in design and optimization of such devices, in particular if it could be tuned by applying a variable external electric field. However, in conventional materials, the bandgap is fixed by their crystalline structure, preventing such bandgap control. Here we demonstrate the realization of a widely tunable electronic bandgap in electrically gated bilayer graphene. Using a dual-gate bilayer graphene field-effect transistor (FET) and infrared microspectroscopy, we demonstrate a gate-controlled, continuously tunable bandgap of up to 250 meV. Our technique avoids uncontrolled chemical doping and provides direct evidence of a widely tunable bandgap -- spanning a spectral range from zero to mid-infrared -- that has eluded previous attempts. Combined with the remarkable electrical transport properties of such systems, this electrostatic bandgap control suggests novel nanoelectronic and nanophotonic device applications based on graphene.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- Advanced Light Source Division; Earth Sciences Division
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 974550
- Report Number(s):
- LBNL-2786E; TRN: US201007%%797
- Journal Information:
- Nature, Journal Name: Nature
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
77 NANOSCIENCE AND NANOTECHNOLOGY
DESIGN
ELECTRIC FIELDS
ELECTROSTATICS
FIELD EFFECT TRANSISTORS
FLEXIBILITY
LASERS
OPTICAL PROPERTIES
OPTIMIZATION
PHOTODIODES
PHYSICS
P-N JUNCTIONS
SEMICONDUCTOR DEVICES
TRANSISTORS
TRANSPORT
electrically gated bandgap bilayer graphene dual-gate gate-controlled
transport
nanophotonic