Search
Menu

Graphene Photodetector Demonstrates Speed, High Responsivity

Facebook X LinkedIn Email
A new photodetector, made with graphene, can operate across a broader range of wavelengths and process images faster than existing photodetectors. The detector is also more sensitive to low levels of light than current technology.

Graphene photodetector, UCLA.
The photodetector operates across a broad range of light, processes images more quickly, and is more sensitive to low levels of light than current technology. Courtesy of UCLA Engineering.

Researchers from University of California, Los Angeles (UCLA) fabricated the photodetector using photoconductive nanostructures based on gold-patched graphene nanostripes. They laid stripes of graphene over a silicon dioxide layer; then they created a series of comb-shaped nanoscale patterns made from gold, with “teeth” about 100 nm wide. The graphene nanostripes act as a net to catch incoming photons. The graphene then converts the photons into an electrical signal. The gold comb-shaped nanopatterns quickly transfer that information into a processor, which produces a corresponding high-quality image, even under low-light conditions.

Through this approach, the team achieved high responsivity without the use of bandwidth-limiting and speed-limiting quantum dots, defect states, or tunneling barriers.

The graphene photodetector demonstrated high-responsivity (ampere per watt; A/W) photodetection from the visible to the IR regime of 0.6 A/W at 0.8 μm, and 11.5 A/W at 20 μm, with operation speeds exceeding 50 GHz. The results indicate an improvement of the response times by more than seven orders of magnitude and an increase in bandwidths of one order of magnitude, compared to higher-responsivity graphene photodetectors based on quantum dots and tunneling barriers.


“We specifically designed the dimensions of the graphene nanostripes and their metal patches such that incoming visible and infrared light is tightly confined inside them," said researcher Semih Cakmakyapan. "This design efficiently produces an electrical signal that follows ultrafast and subtle variations in the light’s intensity over the entire spectral range, from visible to infrared.”

The team believes that the combination of broadband and ultrafast photodetection with high responsivity could have an impact on future hyperspectral imaging and sensing systems. Researchers said that to further enhance performance, the symmetric gold patches could be replaced with asymmetric metal patches; this could lead to symmetry breaking and enable bias-free, low-dark-current device operation.

“Our photodetector could extend the scope and potential uses of photodetectors in imaging and sensing systems," said professor Mona Jarrahi. "It could dramatically improve thermal imaging in night vision or in medical diagnosis applications where subtle differences in temperatures can give doctors a lot of information on their patients. It could also be used in environmental sensing technologies to more accurately identify the concentration of pollutants.”

The research was published in Light: Science & Applications (doi:10.1038/s41377-018-0020-2).

Published: July 2018
Glossary
nanopositioning
Nanopositioning refers to the precise and controlled movement or manipulation of objects or components at the nanometer scale. This technology enables the positioning of objects with extremely high accuracy and resolution, typically in the range of nanometers or even sub-nanometer levels. Nanopositioning systems are employed in various scientific, industrial, and research applications where ultra-precise positioning is required. Key features and aspects of nanopositioning include: Small...
hyperspectral imaging
Hyperspectral imaging is an advanced imaging technique that captures and processes information from across the electromagnetic spectrum. Unlike traditional imaging systems that record only a few spectral bands (such as red, green, and blue in visible light), hyperspectral imaging collects data in numerous contiguous bands, covering a wide range of wavelengths. This extended spectral coverage enables detailed analysis and characterization of materials based on their spectral signatures. Key...
photodetector
A photodetector, also known as a photosensor or photodiode, is a device that detects and converts light into an electrical signal. Photodetectors are widely used in various applications, ranging from simple light sensing to more complex tasks such as imaging and communication. Key features and principles of photodetectors include: Light sensing: The primary function of a photodetector is to sense or detect light. When photons (particles of light) strike the active area of the photodetector,...
graphene
Graphene is a two-dimensional allotrope of carbon consisting of a single layer of carbon atoms arranged in a hexagonal lattice pattern. It is the basic building block of other carbon-based materials such as graphite, carbon nanotubes, and fullerenes (e.g., buckyballs). Graphene has garnered significant attention due to its remarkable properties, making it one of the most studied materials in the field of nanotechnology. Key properties of graphene include: Two-dimensional structure:...
nano
An SI prefix meaning one billionth (10-9). Nano can also be used to indicate the study of atoms, molecules and other structures and particles on the nanometer scale. Nano-optics (also referred to as nanophotonics), for example, is the study of how light and light-matter interactions behave on the nanometer scale. See nanophotonics.
Research & TechnologyAmericaseducationImagingLight SourcesNanopositioningOpticsSensors & Detectorshyperspectral imagingthermal sensingmedical imagingphotodetectorgraphenegraphene photodetectorMaterialsnanoenvironmentUCLA Samueli School of EngineeringTech Pulse

We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.