Nav: Home

Defects enable RoHS-compliant, high-performance infrared photodetectors

April 02, 2019

There has been an urgent need in consumer electronics for infrared optoelectronics including light emitting diodes and photodetectors. To date, however, infrared optoelectronics are served by costly CMOS incompatible III-V semiconductors. Recently a new class of semiconductors that address the CMOS compatibility issue has emerged based on colloidal quantum dots. When it comes to consumer electronics the use of RoHS compliant materials is a prerequisite and therefore there is a strong need for the development of high performance devices based on environmentally friendly elements, something that in the infrared had remained elusive.

To address this challenge ICFO researchers have discovered that by controlling defects in materials one can extend the semiconductor's spectral reach beyond its bandgap, expanding thereby the material availability for the infrared part of spectrum.

In a recent study published in Advanced Optical Materials, ICFO researchers Dr. Nengjie Huo, Dr. Alberto Figueroba, Dr. Y. Yang, Dr. Sotirios Christodoulou, Dr. Alexandros Stavrinadis, led by ICREA Prof at ICFO Gerasimos Konstantatos, in collaboration with Prof. C. Magén from Univ. of Zaragoza, have reported on the development of an infrared detector using Bismuth Sulphide, which has proven to have fast and high photo-response levels in the short-wave infrared range thanks to the formation of defects in the material.

In their experiment, the team of researchers fabricated a photoconductive detector, depositing a very thin layer of Bi2S3 flakes onto a Si/SiO2 substrate. Once built, the team was able to observe that the Bi2S3 flakes possessed sulphur vacancies or defects in the material (sulphur-deficient), which created extended in-gap states, which allowed an increased absorption of light below the bandgap value of Bi2S3, that is sub-bandgap. Such features led to a high gain, low noise and, subsequently, a high sensitivity photodetector.

To shed insights in the sulphur deficiency mechanism, they built a second photodetector and synthesized the Bi2S3 crystal, by performing a sulfurization process (changing the concentration percentages of Bi and S in the crystal) and subsequently refilling the sulphur vacancies. In doing this, they were able to observe that the photodetector had a much faster response time but was limited to the spectral range in the near infrared. Thus, to improve the response time without sacrificing its spectral coverage into the infrared, they carried out a mild chemical treatment on the sulphur-deficient-based detector, through a surface passivation process of the crystal. Completing the treatment, they observed that the time response had reached a value of approximately 10ms for the infrared and visible light range, 50 times faster than the original sulphur deficient-based detector.

The results of this study provide new insights into the role atomic vacancies play in the electronic structure and how sub-bandgap photoresponse effects can enable ultrasensitive, fast, and broadband photodetectors.
This work has been partially supported by the European Commission's Graphene Flagship initiative.

ICFO - The Institute of Photonic Sciences was founded in 2002 by the Government of Catalonia and the Universitat Politècnica de Catalunya (UPC), both of which are members of its board of trustees along with the Cellex and Mir-Puig Foundations, philanthropic entities that have played a critical role in the advancement of the institute since 2007. Located in the Mediterranean Technology Park in the metropolitan area of Barcelona, the institute currently hosts 400 people, organized in 26 research groups in 60 state-of-the-art research laboratories. Research lines encompass diverse areas in which photonics plays a decisive role, with an emphasis on basic and applied themes relevant to medicine and biology, advanced imaging techniques, information technologies, a range of environmental sensors, tunable and ultra-fast lasers, quantum science, photovoltaics and the properties and applications of nano-materials such as graphene, among others. In addition to two state awarded Severo Ochoa accreditations of excellence, ICFOnians have been awarded 15 ICREA Professorships and 32 European Research Council grants. ICFO participates actively in the European Technological Platform Photonics21 and is also very proactive in fostering entrepreneurial activities, spin-off creation, and creating collaborations and links between industry and ICFO researchers. To date, ICFO has helped create 7 start-up companies.

ICFO-The Institute of Photonic Sciences

Related Photodetectors Articles:

Defects enable RoHS-compliant, high-performance infrared photodetectors
A study led by ICFO researchers reports on a highly sensitive CMOS compatible broadband photodetector by tailoring material defects.
New method improves infrared imaging performance
By successfully suppressing spectral cross-talk in dual-band photodetectors, Professor Manijeh Razeghi has opened the door to a new generation of infrared imaging devices with applications in medicine as well as defense and security.
Innovative technique could pave way for new generation of flexible electronic components
Researchers at the University of Exeter have developed an innovative technique that could help create the next generation of everyday flexible electronics.
Perovskites -- materials of the future in optical communication
Researchers at the universities in Linköping and Shenzhen have shown how an inorganic perovskite can be made into a cheap and efficient photodetector that transfers both text and music.
A trick of the light
Argonne researchers are using nanoparticles to make photodetectors better able to handle the ultraviolet radiation produced in high-energy physics experiments.
SUTD researchers resolve a major mystery in 2D material electronics
SUTD researchers have discovered a one-size-fits-all master equation that shall pave the way towards better design of 2D material electronics.
Research brief: Researchers 3D print prototype for 'bionic eye'
A team of researchers at the University of Minnesota have, for the first time, fully 3D printed an array of light receptors on a hemispherical surface.
Nano-imaging of intersubband transitions in few-layer 2-D materials
A study in Nature Nanotechnology reports on the first observation of intersubband transitions in 2-D materials via scattering scanning near-field optical microscopy.
Fast visible-UV light nanobelt photodetector
Here, we report a fast-response CdSCdSxTe1-x-CdTe core-shell nanobelt photodetector with a rise time of 11 μs, which is the fastest among CdS based photodetectors reported previously.
Scientists create a UV detector based on nanocrystals synthesized by using ion implantation
Scientists at the Lobachevsky University have been working for several years to develop solar-blind photodetectors operating in the UV spectral band.

Related Photodetectors Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...