Coffee-ring effect leads to crystallization control in semiconductors

March 03, 2017

A chance observation of crystals forming a mark that resembled the stain of a coffee cup left on a table has led to the growth of customized polycrystals with implications for faster and more versatile semiconductors.

Thin-film semiconductors are the foundation of a vast array of electronic and optoelectronic devices. They are generally fabricated by crystallization processes that yield polycrystals with a chaotic mix of individual crystals of different orientations and sizes.

Significant advances in controlling crystallization has been made by a team led by Professor Aram Amassian of Material Science and Engineering at KAUST. The group included individuals from the KAUST Solar Center and others from the University's Physical Science and Engineering Division in collaboration with Cornell University. Amassian said, "There is no longer a need to settle for random and incoherent crystallization."

The team's recent discovery began when Dr. Liyang Yu of the KAUST team noticed that a droplet of liquid semiconductor material dried to form an outer coffee-ring shape that was much thicker than the material at the center. When he induced the material to crystallize, the outer ring crystallized first.

"This hinted that local thickness matters for initiating crystallization," said Amassian, which went against the prevailing understanding of how polycrystal films form.

This anomaly led the researchers to delve deeper. They found that the thickness of the crystallizing film could be used to manipulate the crystallization of many materials (see top image). Most crucially, tinkering with the thickness also allowed fine control over the position and orientation of the crystals in different regions of a semiconductor.

"We discovered how to achieve excellent semiconductor properties everywhere in a polycrystal film," said Amassian. He explained that seeding different patterns of crystallization at different locations also allowed the researchers to create bespoke arrays that can now be used in electronic circuits (see bottom image).

This is a huge improvement to the conventional practice of making do with materials whose good properties are not sustained throughout the entire polycrystal nor whose functions at different regions can be controlled.

"We can now make customized polycrystals on demand," Amassian said.

Amassian hopes that this development will lead to high-quality, tailored polycrystal semiconductors to promote advances in optoelectronics, photovoltaics and printed electronic components. The method has the potential to bring more efficient consumer electronic devices, some with flexible and lightweight parts, new solar power generating systems and advances in medical electronics. And all thanks to the chance observation of an odd pattern in a semiconductor droplet.

The team will now explore ways to move their work beyond the laboratory through industry partnerships and research collaborations.
-end-


King Abdullah University of Science & Technology (KAUST)

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.