Scientists pioneer new generation of semiconductor neutron detector

January 15, 2020

Whether you are trying to detect a possible radiation signature from a suspicious package or vehicle, or you are measuring power output in a nuclear reactor, being able to detect neutrons efficiently and precisely represents a significant challenge.

Most neutron detectors work based on one of two different technologies. Some, like those based on helium, are gas-filled. Others, like those based on lithium or boron, involve scintillators that take absorbed neutrons and emit light in response. In neither case are neutrons converted to electrical current and thus a directly readable signal.

In a new study from the U.S. Department of Energy's (DOE) Argonne National Laboratory and Northwestern University, scientists have developed a new type of semiconductor neutron detector that boosts detection rates by reducing the number of steps involved in neutron capture and transduction.

"Our material shows that semiconductors that have been previously discounted can be promising if you have the right crystal." -- Mercouri Kanatzidis, Argonne materials scientist

This new material, called LiInP2Se6, converts neutrons into pairs of charged electrons and holes. When a voltage is applied to the material, the electron-hole pairs separate, and a current is generated.

"The true advantage of this semiconductor compared to other types of materials is that it is able to directly detect thermal neutrons," said Argonne materials scientist Duck Young Chung, one of the authors of the study. "That improves the sensitivity of this detector because it doesn't require an amplifier and a whole process."

When neutrons are converted into charged particles in scintillators, many of them are lost in the process of generating a current and being detected. This is because the absorbent lithium atoms are dispersed in a relatively low concentration in these materials, requiring a thicker layer to absorb the neutrons. By contrast, the neutron absorbent part of the semiconductor is much more concentrated, reducing the loss of signal.

By contrast, semiconductor-based technologies have lower energy resolution than scintillators in general, representing a higher sensitivity to the absorbed neutrons. "Instead of having a multiple step process in which you lose a lot of your particles, you now have much higher sensitivity," Chung said.

Northwestern graduate student Daniel Chica and postdoctoral researcher Yihui He succeeded in producing crystals of high quality for 6Li-enriched LiInP2Se6, which they made into a simple device capable of thermal neutron detection when exposed to a weak source. 

The sensitivity of the detector registers as a higher and narrower peak reading of a characteristic energy signature associated with the neutrons being detected. It is for this reason that another advantage of the semiconductor material could lie in its ability to do what researchers call "neutron forensics."

"Essentially, by knowing the energy of the neutrons you are detecting, you can determine exactly what isotope produced them," said Argonne materials scientist and Northwestern University professor Mercouri Kanatzidis. 

Previous semiconductor materials for neutron detection have been difficult and expensive to make. "There are only a few materials that have been studied as semiconductors for neutron detection, and there isn't a lot of research being done into new options," Chung said. "But studies like this might lay the groundwork for new studies that could drive down the cost."

According to Kanatzidis, this study could lead to a renaissance of interest in semiconductor technology for neutron detection. "The idea for this has existed, but no one has found the right material to demonstrate it; other materials were plagued by materials issues that caused people to give up because they could not attain the proper performance," he said. "Here our material shows that semiconductors that have been previously discounted can be promising if you have the right crystal."
-end-
A paper based on the study, "Direct thermal neutron detection by the 2D semiconductor LiInP2Se6," appeared in the January 15 issue of Nature. Additional authors of the study included Northwestern University's Kyle McCall, Giancarlo Trimarchi, Zhifu Liu, and Bruce Wessels and Argonne's Rahmi Pak and Patrick De Lurgio.

The research was funded by an Argonne Laboratory-Directed Research and Development grant as well as the National Science Foundation.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.

The U.S. Department of Energy's Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.

DOE/Argonne National Laboratory

Related Semiconductor Articles from Brightsurf:

Blue phosphorus: How a semiconductor becomes a metal
Blue phosphorus, an atomically thin synthetic semiconductor, becomes metallic as soon as it is converted into a double layer.

A new method to measure optical absorption in semiconductor crystals
Tohoku University researchers have revealed more details about omnidirectional photoluminescence (ODPL) spectroscopy - a method for probing semiconducting crystals with light to detect defects and impurities.

Medical robotic hand? Rubbery semiconductor makes it possible
A medical robotic hand could allow doctors to more accurately diagnose and treat people from halfway around the world, but currently available technologies aren't good enough to match the in-person experience.

Laser allows solid-state refrigeration of a semiconductor material
A team from the University of Washington used an infrared laser to cool a solid semiconductor by at least 20 degrees C, or 36 F, below room temperature, as they report in a paper published June 23 in Nature Communications.

Scientists create smallest semiconductor laser
An international team of researchers announced the development of the world's most compact semiconductor laser that works in the visible range at room temperature.

Clemson researcher's novel MOF is potential next-gen semiconductor
Clemson professor Sourav Saha demonstrated a novel double-helical metal organic framework architecture in a partially oxidized form that conducts electricity, potentially making it a next-generation semiconductor.

A gold butterfly can make its own semiconductor skin
A nanoscale gold butterfly provides a more precise route for growing/synthesizing nanosized semiconductors that can be used in nano-lasers and other applications.

Scientists pioneer new generation of semiconductor neutron detector
In a new study, scientists have developed a new type of semiconductor neutron detector that boosts detection rates by reducing the number of steps involved in neutron capture and transduction.

Scientists see defects in potential new semiconductor
A research team has reported seeing, for the first time, atomic scale defects that dictate the properties of a new and powerful semiconductor.

Bending an organic semiconductor can boost electrical flow
Slightly bending semiconductors made of organic materials can roughly double the speed of electricity flowing through them and could benefit next-generation electronics such as sensors and solar cells, according to Rutgers-led research.

Read More: Semiconductor News and Semiconductor Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.