Researchers Use Copper Indium Selenide Quantum Dots to Reduce the Toxicity of Transistors

Researchers from Los Alamos National Laboratory and the University of California (UC), Irvine created a manufacturing-friendly way of creating electronic devices. In their research paper published in the October 19 issue of Nature Communications, the team detailed their use of copper indium selenide (CuInSe2) quantum dots to reduce the toxicity of their transistors and to integrate two transistor types in the same quantum dot layer. 

 

Gold and indium were used to define p- and n-type transistors. Image used courtesy of Los Alamos National Laboratory

 

What is Quantum Dot Technology?

A quantum colloidal dot is composed of a crystalline inorganic semiconductor core and an outer layer of organic molecules. The nature of the hybrid inorganic and organic structure provides quantum dots with well-known advantages of traditional semiconductors and the versatility of molecular systems. 

They can be constructed and processed into functional electronic devices via easily scalable and low-cost methods. There is the potential to use such technology in medical diagnostics, security, consumer electronics, and digital signage. Other flexible electronic devices could also be created using quantum dots, ones that could be printed onto a variety of surfaces including paper, plastic, or human skin. 

 

Integrating N- and P-Type Transistors  

Complementary metal-oxide semiconductors (CMOS) technology utilizes a system design and particular processes for the build of reliable, power-efficient digital logic from n-type and p-type transistors. Until now, the use of quantum dots in CMOS circuits has been limited by the difficulty of integrating complementary n- and p-type devices within the same quantum dot layer. 

Los Alamos and UC researchers used CuInSe2 to eliminate the use of toxic heavy metals and bring together n- and p-transistors in the same quantum dot layer. In their new paper, Klimov and colleagues used gold and indium to define p- and n-type transistors respectively. These pre-patterned metal contacts were then covered over with a common quantum dot layer via a technique known as spin-coating to complete the device design.

In a recent news release, Los Alamos physicist and lead author of the research, Victor Klimov commented that, This approach permits straightforward integration of an arbitrary number of complementary p- and n-type transistors into the same quantum dot layer prepared as a continuous, un-patterned film via standard spin-coating.”

 

The Los Alamos National Laboratory is a United States Department of Energy national laboratory situated in New Mexico. Image used courtesy of Los Alamos National Laboratory

 

Klimov and the team showed that they could achieve the integration of complementary devices and integrated logic circuits were observed to be well-behaved with a low-switching-voltage (0–5 V). Low voltages achieved in this research are thought to be compatible with standard CMOS electronics. 

“Potential applications of the new approach to electronic devices based on non-toxic quantum dots include printable circuits, flexible displays, lab-on-a-chip diagnostics, wearable devices, medical testing, smart implants, and biometrics,” Klimov said.