Nav: Home

Notre Dame researchers find transition point in semiconductor nanomaterials

August 31, 2016

Collaborative research at Notre Dame has demonstrated that electronic interactions play a significant role in the dimensional crossover of semiconductor nanomaterials. The laboratory of Masaru Kuno, professor of chemistry and biochemistry, and the condensed matter theory group of Boldizsár Jankó, professor of physics, have now shown that a critical length scale marks the transition between a zero-dimensional, quantum dot and a one-dimensional nanowire.

The findings, "Dimensional crossover in semiconductor nanostructures," were published in Nature Communications. Matthew P. McDonald and Rusha Chatterjee of Kuno's laboratory and Jixin Si of Jankó's group are also authors of the publication.

A quantum dot structure possesses the same physical dimensions in every direction while a quantum wire exhibits one dimension longer than the others. This means that quantum dots and nanowires made of the same material exhibit different optical and electrical responses at the nanoscale since these properties are exquisitely size- and shape-dependent. Understanding the size- and shape-dependent evolution of nanomaterial properties has therefore been a central focus of nanoscience over the last two decades. However, it has never been definitively established how a quantum dot evolves into a nanowire as its aspect ratio is made progressively larger. Do quantum properties evolve gradually or do they suddenly transition?

Kuno's laboratory discovered that a critical length exists where a quantum dot becomes nanowire-like. The researchers achieved this breakthrough by conducting the first direct, single particle absorption measurements on individual semiconductor nanorods, an intermediate species between quantum dots and nanowires. Single particle rather than ensemble measurements were used to avoid the effects of sample inhomogeneities. Furthermore, an absorption approach rather than an often-used emission approach was employed to circumvent existing limitations of modern emission-based single particle microscopy-namely, its restriction to the observation of highly fluorescent specimens.

The discovery marks a significant advance in our understanding of the size- and shape-dependent quantum mechanical response of semiconductor nanostructures. "All of the introductory-level solid state or semiconductor textbooks need to revise what they say about dimensional crossover," Jankó said. "This is another example where interactions makes things completely different." Beyond this, Kuno suggests that the single particle absorption approach advanced in the study "has practical, real-world applications, maybe 40 years down the road." Examples include the generic and label-free ultrasensitive detection of chemical and biomolecular species of paramount interest within the spheres of homeland security as well public health.

Kuno's group performed the experiments that led to the discovery while Jankó's group provided theoretical support.
-end-


University of Notre Dame

Related Quantum Dots Articles:

Graphene and quantum dots put in motion a CMOS-integrated camera that can see the invisible
ICFO develops the first graphene-based camera, capable of imaging visible and infrared light at the same time.
Platelets instead of quantum dots
A team of researchers led by ETH Zurich professor David Norris has developed a model to clarify the general mechanism of nanoplatelet formation.
Quantum dots illuminate transport within the cell
Biophysicists from Utrecht University have developed a strategy for using light-emitting nanocrystals as a marker in living cells.
'Flying saucer' quantum dots hold secret to brighter, better lasers
By carefully controlling the size of the quantum dots, the researchers can 'tune' the frequency, or color, of the emitted light to any desired value.
'Flying saucer' colloidal quantum dots produce brighter, better lasers
A multi-institutional team of researchers from Canada and the US has demonstrated steady state lasing with solution-processed nanoparticles called 'colloidal quantum dots,' an important step on the path to improving laser tools for fiber optics, video projectors and more accurate medical testing technology.
More Quantum Dots News and Quantum Dots Current Events

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

Teaching For Better Humans
More than test scores or good grades — what do kids need to prepare them for the future? This hour, guest host Manoush Zomorodi and TED speakers explore how to help children grow into better humans, in and out of the classroom. Guests include educators Olympia Della Flora and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#535 Superior
Apologies for the delay getting this week's episode out! A technical glitch slowed us down, but all is once again well. This week, we look at the often troubling intertwining of science and race: its long history, its ability to persist even during periods of disrepute, and the current forms it takes as it resurfaces, leveraging the internet and nationalism to buoy itself. We speak with Angela Saini, independent journalist and author of the new book "Superior: The Return of Race Science", about where race science went and how it's coming back.