Engineers at Caltech have for the first time developed nanostructure a light detector. Combines two disparate technologies nanophotonic, which manipulates light at the nanoscale. Thermoelectric 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 distinguish between different colors of light or heat used in variety of applications. Including satellites that study changing vegetation and landscape on the earth and medical imagers. Distinguish between healthy and cancerous cells based on their color variations.
The new detector operates about 10 to 100 times faster than current comparable thermoelectric devices. Capable of detecting light across a wider range of the electromagnetic spectrum than traditional light detectors. In traditional light detectors incoming photons of light absorbed in semiconductor. Excite electrons captured by the detector. The movement of light-excited electrons produces electric current signal measured and quantified. While effective, this type of system makes it difficult to see infrared light. Made up of lower-energy photons than those in visible light.
Nano-structures generate electric current to the light wavelength absorbed
Because the new detectors are potentially capable of capturing infrared wavelengths of sunlight. The heat not collected efficiently by conventional solar materials. Technology could lead to better solar cells and imaging devices.
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. Nanostructures absorb light, generate electric current with strength corresponds to the light wavelength absorbed.
The detectors fabricated in the Kavli Nanoscience Institute cleanroom at Caltech, the team created subwavelength structures using 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.