Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Creativity leads to measuring ultrafast, thin photodetector

Abstract:
Making an incredibly fast photodetector is one thing, but actually measuring its speed is another.

Creativity leads to measuring ultrafast, thin photodetector

Ithaca, NY | Posted on December 21st, 2015

Graduate student Haining Wang came up with an inventive way of measuring the near-instantaneous electrical current generated using a light detector that he and a team of Cornell engineers made using an atomically thin material.

The team, headed by Farhan Rana, associate professor in the School of Electrical and Computer Engineering, measured the ultrafast response of their two-dimensional photodetector using a strobe-like process called two-pulse photovoltage correlation.

The team's paper, "Ultrafast response of monolayer molybdenum disulfide photodetectors," was published in Nature Communications.

"It was very clever," Rana said of Wang's idea. "He came up with this idea of essentially hitting the device with an optical pulse [to initiate an electrical charge] and after a small delay, hitting it with the pulse again. By varying the time between the first and second pulse, and looking at the response of the device as a result, you can sort of see what the intrinsic speed of the device is."

Rana's team used a 3-atoms-thick sheet of molybdenum disulfide (MoS2), a material Rana and others have tested previously in photodetection studies. Photodetection is used in various high-speed optoelectronic applications, including optical fiber networks.

According to Wang's experimentation, the MoS2 photodetector had intrinsic response times as short as 3 picoseconds; a picosecond is one-trillionth of a second. Co-author Wang said the speed at which the MoS2 detector responds is vastly superior to current technology, and is partly due to the extremely short distance the charges generated by light must travel before making it out of the device and into the external electrical circuit.

"State-of-the-art optical communication links work at around 10 GHz per channel, so if you make 10 channels in parallel, you have a 100 GHz optical communication link," he said. "We find that this single device can work up to 300 GHz, which is an amazing speed."

Wang also said that, despite being just 3-atoms thick, MoS2 is "extremely easy to make" and relatively inexpensive, adding to its appeal.

As with all photodetectors, however, the downside is the low quantum efficiency, which is a measure of the number of charges generated by the detector in the external circuit per incident photon.

In the Rana team's work, only a small percentage of the light-generated charges - 1 to 2 percent - were able to escape the photodetector and make it into the external circuit; most recombined inside the device, producing heat. Market-available photodetector materials such as silicon and gallium arsenide, while generally much slower, have efficiencies of anywhere from 50 to 90 percent.

"That's the tradeoff of these devices," Rana said. "Every photodetector ever made has always had to face the efficiency-speed tradeoff."

Further research by the group will include a discovery made by both Rana's team and a research group at the University of California, Berkeley: coating the sample with a chemical that will "basically kill the recombination completely," Rana said.

"So you have to play around with these material surfaces and make sure you're attaching the right molecules and atoms to it on the outside," Rana said.

The Berkeley group reported in November an efficiency of 95 percent using their chemically coated MoS2 photodetector.

Rana said the photodetection technology will play a major role in emerging fields, such as LiFi - using light as a source of wireless communication. He said windows and walls could be coated with atomically thin layers of material that would interact with light and carry Internet signals.

###

Other co-authors include former graduate students Changjian Zhang and Weimin Chan, and Sandip Tiwari, the Charles N. Mellowes Professor of Engineering.

Their research was supported by the Cornell Center for Materials Research, under a National Science Foundation grant, the Air Force Office of Scientific Research, the Office of Naval Research, as well as an NSF grant to the Cornell NanoScale Science and Technology Facility.

####

For more information, please click here

Contacts:
Daryl Lovell

607-254-4799

Copyright © Cornell University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

RELATED JOURNAL ARTICLE

Related News Press

News and information

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

Wireless/telecommunications/RF/Antennas/Microwaves

HKUST researchers develop new integration technique for efficient coupling of III-V and silicon February 16th, 2024

Optical-fiber based single-photon light source at room temperature for next-generation quantum processing: Ytterbium-doped optical fibers are expected to pave the way for cost-effective quantum technologies November 3rd, 2023

Chip-based dispersion compensation for faster fibre internet: SUTD scientists developed a novel CMOS-compatible, slow-light-based transmission grating device for the dispersion compensation of high-speed data, significantly lowering data transmission errors and paving the way for June 30th, 2023

Researchers demonstrate co-propagation of quantum and classical signals: Study shows that quantum encryption can be implemented in existing fiber networks January 20th, 2023

Govt.-Legislation/Regulation/Funding/Policy

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024

Sensors

$900,000 awarded to optimize graphene energy harvesting devices: The WoodNext Foundation's commitment to U of A physicist Paul Thibado will be used to develop sensor systems compatible with six different power sources January 12th, 2024

A color-based sensor to emulate skin's sensitivity: In a step toward more autonomous soft robots and wearable technologies, EPFL researchers have created a device that uses color to simultaneously sense multiple mechanical and temperature stimuli December 8th, 2023

New tools will help study quantum chemistry aboard the International Space Station: Rochester Professor Nicholas Bigelow helped develop experiments conducted at NASA’s Cold Atom Lab to probe the fundamental nature of the world around us November 17th, 2023

TU Delft researchers discover new ultra strong material for microchip sensors: A material that doesn't just rival the strength of diamonds and graphene, but boasts a yield strength 10 times greater than Kevlar, renowned for its use in bulletproof vests November 3rd, 2023

Discoveries

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

High-tech 'paint' could spare patients repeated surgeries March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Materials/Metamaterials/Magnetoresistance

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Focused ion beam technology: A single tool for a wide range of applications January 12th, 2024

Catalytic combo converts CO2 to solid carbon nanofibers: Tandem electrocatalytic-thermocatalytic conversion could help offset emissions of potent greenhouse gas by locking carbon away in a useful material January 12th, 2024

Announcements

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Military

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

New chip opens door to AI computing at light speed February 16th, 2024

NRL discovers two-dimensional waveguides February 16th, 2024

Research partnerships

Researchers’ approach may protect quantum computers from attacks March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

'Sudden death' of quantum fluctuations defies current theories of superconductivity: Study challenges the conventional wisdom of superconducting quantum transitions January 12th, 2024

Development of zinc oxide nanopagoda array photoelectrode: photoelectrochemical water-splitting hydrogen production January 12th, 2024

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project