Skip to main content

Light detector with a combination of nanophotonics and thermoelectrics

Engineers at Caltech have for the first time developed a light detector that combines two disparate technologies -- nanophotonics, which manipulates light at the nanoscale, and thermoelectrics, which translates temperature differences directly into electron voltage -- to distinguish different wavelengths (colors) of light, including both visible and infrared wavelengths, at high resolution.
Light detectors that distinguish between different colors of light or heat are used in a variety of applications, including satellites that study changing vegetation and landscape on Earth and medical imagers that distinguish between healthy and cancerous cells based on their color variations.
The new detector, described in a paper in Nature Nanotechnologyon May 22, operates about 10 to 100 times faster than current comparable thermoelectric devices and is capable of detecting light across a wider range of the electromagnetic spectrum than traditional light detectors. In traditional light detectors, incoming photons of light are absorbed in a semiconductor and excite electrons that are captured by the detector. The movement of these light-excited electrons produces an electric current -- a signal -- that can be measured and quantified. While effective, this type of system makes it difficult to "see" infrared light, which is made up of lower-energy photons than those in visible light.
Because the new detectors are potentially capable of capturing infrared wavelengths of sunlight and heat that cannot be collected efficiently by conventional solar materials, the technology could lead to better solar cells and imaging devices.
"In nanophotonics, we study the way light interacts with structures that are much smaller than the optical wavelength itself, which results in extreme confinement of light. In this work, we have combined this attribute with the power conversion characteristics of thermoelectrics to enable a new type of optoelectronic device," says Harry Atwater, corresponding author of the study. Atwater is the Howard Hughes Professor of Applied Physics and Materials Science in the Division of Engineering and Applied Science at Caltech, and director of the Joint Center for Artificial Photosynthesis (JCAP). JCAP is a Department of Energy (DOE) Energy Innovation Hub focused on developing a cost-effective method of turning sunlight, water, and carbon dioxide into fuel. It is led by Caltech with Berkeley Lab as a major partner.
Atwater's team built materials with nanostructures that are hundreds of nanometers wide -- smaller even than the wavelengths of light that represent the visible spectrum, which ranges from about 400 to 700 nanometers.
The researchers created nanostructures with a variety of widths, that absorb different wavelengths -- colors -- of light. When these nanostructures absorb light, they generate an electric current with a strength that corresponds to the light wavelength that is absorbed.
The detectors were fabricated in the Kavli Nanoscience Institute cleanroom at Caltech, where the team created subwavelength structures using a combination of vapor deposition (which condenses atom-thin layers of material on a surface from an element-rich mist) and electron beam lithography (which then cuts nanoscale patterns in that material using a focused beam of electrons). The structures, which resonate and generate a signal when they absorb photons with specific wavelengths, were created from alloys with well-known thermoelectric properties, but the research is applicable to a wide range of materials, the authors say.
"This research is a bridge between two research fields, nanophotonics and thermoelectrics, that don't often interact, and creates an avenue for collaboration," says graduate student Kelly Mauser (MS '16), lead author of the Nature Nanotechnology study. "There is a plethora of unexplored and exciting application and research opportunities at the junction of these two fields."
Journal Reference:
  1. Kelly W. Mauser, Seyoon Kim, Slobodan Mitrovic, Dagny Fleischman, Ragip Pala, K. C. Schwab, Harry A. Atwater. Resonant thermoelectric nanophotonics. Nature Nanotechnology, 2017; DOI: 10.1038/nnano.2017.87

Comments

Post a Comment

Popular posts from this blog

Nanoimprinting accelerating the fabrication of nano-optical devices

Combining speed with incredible precision, a team of researchers has developed a way to print a nanoscale imaging probe onto the tip of a glass fiber as thin as a human hair, accelerating the production of the promising new device from several per month to several per day. The high-throughput fabrication technique opens the door for the widespread adoption of this and other nano-optical structures, which squeeze and manipulate light in ways that are unachievable by conventional optics. Nano-optics have the potential to be used for imaging, sensing, and spectroscopy, and could help scientists improve solar cells, design better drugs, and make faster semiconductors. A big obstacle to the technology's commercial use, however, is its time-consuming production process. The new fabrication method, called fiber nanoimprinting, could unplug this bottleneck. It was developed by scientists at the Molecular Foundry, located at the Department of Energy's Lawrence Berkeley Nat...
Post a Comment
Read more

Intel's upcoming 10-nanometer chip manufacturing technology

At long last, chip giant  Intel  (NASDAQ: INTC) opened up about its upcoming 10-nanometer chip manufacturing technology, at its first-ever Technology and Manufacturing Day. The company has -- frustratingly -- kept key details of this technology under wraps for years now, but Intel is now putting them out there for all to see.  Without further ado, let's look at what Intel had to tell us about this new tech. A large jump in density Let's talk performance Competitive comparison and no yield information Image source: Intel. Chipmakers generally like to reduce the area of its transistors with major new technology shifts. This area reduction is important in reducing transistor costs on a yield-normalized basis, a really important factor for product cost. Chipmakers are ultimately able to cram more features and functionality into a chip while maintaining reasonable cost structures. Intel says that in moving from 14 nanometers to 10, it's delivering an incre...
Post a Comment
Read more

Spintronics in place of electronics : Future of IoT

Information technologies of the future will likely use electron spin -- rather than electron charge -- to carry information. But first, scientists need to better understand how to control spin and learn to build the spin equivalent of electronic components, from spin transistors, to spin gates and circuits. Now, researchers have developed a technique to control and measure spin voltage, known as spin chemical potential. The technique, which uses atomic-sized defects in diamonds to measure chemical potential, is essentially a nanoscale spin multimeter that allows measurements in chip-scale devices. The research is published in  Science . "There is growing interest in insulating materials that can conduct spin," said Amir Yacoby, Professor of Physics in the Department of Physics and of Applied Physics at Harvard John A. Paulson School of Engineering and Applied Sciences and senior author of the paper. "Our work develops a new way to look at these spins in material...
Post a Comment
Read more