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SUNY College of Nanoscale Science and Engineering Scientists Publish Game-Changing Semiconductor Nanosheets Research That Could Revolutionize Cameras in Low-Light Environments

Photocurrent measurements indicate nanosheets exhibit strong response to visible light, enabling advanced photodetectors for a variety of electronic imaging applications

CNSE Postdoctoral Research Scientist
Dr. Mariyappan Shanmugam (left) and
Research Assistant Robin Jacobs-Gedrim
(right)
Leading-edge research by a team of SUNY College of Nanoscale Science and Engineering (CNSE) scientists has been published in ACS Nano after the scientists evaluated ultrathin indium(III) selenide (In2Se3) nanosheets and discovered that their electrical resistance drops significantly when exposed to light. This effect, known as a photoconductive response, can be used to make a photodetector or light sensor, and because the two-dimensional nanosheets exhibited such a strong photoconductive response across a broad light spectrum and simultaneously resist chemical contamination, this research could lead to a revolution in extreme low-light, high-resolution imaging products and applications, such as consumer and professional cameras and video cameras, for example.

CNSE Research Assistant Robin Jacobs-Gedrim, Postdoctoral Research Scientist Dr. Mariyappan Shanmugam; Graduate Research Assistants Nikhil Jain and Christopher Durcan; Undergraduate Research Assistant Michael Murphy; Instructor Dr. Thomas Murray; Professor of Nanoscience Dr. Richard Matyi; Manager of Analytical Facilities and Instructor (retired) Richard Moore, II; and Professor of Nanoengineering Dr. Bin Yu conducted the pioneering research at CNSE’s Albany NanoTech facility, the most advanced research enterprise of its kind in the world.

 
 The smaller, more efficient
photodetectors could lead to
vastly improved imaging equipment
The team combined a variety of cutting-edge tools and methods, including scanning electron microscopy (SEM) to identify the nanosheets; atomic force microscopy (AFM) to measure their thickness; X-ray diffractometry (XRD) and selected area electron diffraction (SAED) combined with high-resolution images from transmission electron microscopy (TEM) to examine nano-layer details such as the crystallographic phase and morphology of the sample; and energy-dispersive X-ray spectrometry (EDS) and auger electron spectrometry (AES) to explore the sample’s homogeneity. As the photoconductive material’s properties were characterized, the CNSE research group found that the material is extremely resistant to contamination. Additionally, the team utilized a green LED to direct pulsed light at the nanosheets and found that they exhibited a reliable response to light and an excellent response time between 18 and 73 milliseconds, indicating that In2Se3 nanosheets could be a highly effective material for real-time imaging purposes.

The nanosheets were also tested for the ability to detect light and for light responsivity, or the ratio of generated photocurrent to incident light power. The researchers noted that the photoconductive response of the nanosheets, which had a thickness of 3.9 nanometers, was demonstrably higher than other 2D photoresistors across a broad light spectrum, including Ultraviolet, visible light, and infrared, making them suitable for use in a wide-range of imaging devices.

“We are thrilled to share the findings of this CNSE research team as it showcases the college’s leading-edge capabilities in this collaborative, high-tech ecosystem which is driving game-changing research to improve everyday technologies,” said Dr. Bin Yu, CNSE Professor of Nanoengineering. “This research is exciting not only because it is a further testament to the caliber of CNSE’s scientists and state-of-the-art facilities, but also because it could lead to more efficient imaging devices for the improvement of healthcare, the advancement of real-time video recording, and the development of more efficient photovoltaics, all of which have the potential to improve countless lives.”

The indium(III) selenide-based research paves the way for a new class of photodetectors that could take advantage of the material’s reliable real-time imaging capability across a broad-spectrum and its ability to work in some of the most extreme low-light conditions, surpassing the qualities of other current-day photodetectors which are used in everything from professional video cameras to MRI machines which rely on light sensors to obtain high-quality images of patients’ organs to aid in the diagnosis of disease. Additionally, the nanosheets are less susceptible to parameter drifting which can cause changes to how accurately the photocurrent is detected over time. The research cited the direct band gap of the nanosheets, which allows for efficient transfer of energy from photons to electrons, as well as the ratio of surface area to volume and its oxide-free surface as the reasons for the material’s improved imaging characteristics.

These novel findings were documented in “Extraordinary Photoresponse in Two-Dimensional In2Se3 Nanosheets,” which was published online by ACS Nano, a high impact journal recognized among top scientists and academicians for the frequency with which its articles are cited in a given year. As an international forum for comprehensive articles on the nanosciences, ACS Nano is published monthly by the American Chemical Society, the world’s largest scientific society, with more than 163,000 members who have access to their publications that aim to foster the communities of chemists and professionals in order to solve scientific challenges by highlighting the most advanced and valuable research for its global readership.

“Currently, the sensors in digital cameras cannot take quality images under low-light conditions. For example, taking a good picture in a dimly lit room requires a long exposure which often results in a blurred image. Hollywood needs to use special lights and filters to make a scene appear dark because filming must be done in well-lit conditions. Future cameras based on indium selenide nanosheet photodetectors may be able to provide a robust, real-time picture in even the most extreme low-light conditions." said Robin Jacobs-Gedrim, CNSE Research Assistant. “Our work could also lead to next-generation applications, making solar panels more efficient, scientific instruments more precise, and medical imaging equipment even more accurate, which shows the power of CNSE’s nano-based research to find technological solutions for a range of industries.”

“The ability to more reliably produce finer images in harsh lighting environments will be invaluable for so many professionals who rely on ever-greater picture quality,” said Dr. Mariyappan Shanmugam, CNSE Postdoctoral Research Scientist. “Leveraging CNSE’s cutting-edge resources and collaborative research environment, these findings are just one more example of how CNSE and New York State have become the epicenter for nanotechnology-based research, development, and commercialization opportunities.”

To view the published article, please visit: http://pubs.acs.org/doi/pdf/10.1021/nn405037s

To view news coverage, please visit:

Times Union:
http://www.timesunion.com/business/article/A-highlight-for-low-light-5180157.php

Laser Focus World:
http://www.laserfocusworld.com/articles/2014/02/suny-nanosheets-could-radically-improve-low-light-imaging.html