Country for PR: Japan
Contributor: Kyodo News JBN
Tuesday, October 25 2022 - 17:00
Insight into Organic Antiambipolar Transistors: WPI-MANA
TSUKUBA, Japan, Oct. 25, 2022 /Kyodo JBN-AsiaNet/ --

International Center for Materials Nanoarchitectonics (WPI-MANA) researchers 
have elucidated the mechanism behind organic antiambipolar transistors (OAATs), 
a new class of transistors with possible applications in artificial 
intelligence and neuromorphic devices. 


Transistors are one of the basic building blocks of modern technology and 
electronics. The emergence of artificial intelligence and brain-like devices 
has brought about a need for multiple logic gate operations to be conducted on 
the same transistor chip. Even the gold standard, complementary metal-oxide 
semiconductor (CMOS) transistors, cannot handle such a large load of 
operations. Hence, the search is on for technologies that can.

Researchers from WPI-MANA, led by Dr. Ryoma Hayakawa, have been investigating a 
new class of transistors, OAATs. OAATs can support multiple logic gate 
operations owing to a unique property called negative differential 
transconductance (NDT). The research team's extensive work, directed by Dr. 
Yutaka Wakayama, has looked to first elucidate the charge-carrier mechanism in 
these devices, and then also apply them to multiple logic gate operations. "We 
needed to know how OAATs work so that they could then be improved upon. So, we 
directly visualized the electron flow in an OAAT, using a technique called 
operando photoemission electron microscopy (PEEM). We were then able to 
understand where the transistor junction gets its exciting switchable 
property," explains Wakayama.

The PEEM experiments showed that a depletion layer is formed at the lateral p-n 
interface; this generates a large potential difference, enhancing electron 
conduction in the transistor. Armed with this knowledge, the research team 
looked at its applicability. "By adjusting input voltages across OAATs, we 
could achieve five different logic gate operations on the same device. We could 
even switch between two logic gates with a given set of inputs," explains 

OAATs are stable and reliable, operating for months. They can surpass CMOS 
devices for many applications. Keeping this in mind, the work done at WPI-MANA 
could lead to a massive reduction in the number of transistors required in 
current integrated circuits and improve their processing ability, enabling the 
development of more advanced technology that can handle large amounts of 

Research Highlights Vol. 79

MANA Research Highlights

Source: International Center for Materials Nanoarchitectonics (WPI-MANA), 
National Institute for Materials Science (NIMS)