Researchers and collaborators at Los Alamos National Laboratory at the University of California, Irvine, used tiny structures called quantum dots to create basic electronic building blocks and used them to assemble functional logic circuits. This innovation is expected to provide a cheaper and easier to manufacture method for complex electronic devices that can be manufactured in chemical laboratories through simple technology based on solutions, and provides many innovative devices that people have been waiting for s component.
Victor Klimov said: “The potential applications of this new approach to non-toxic quantum dot-based electronic devices include printable circuits, flexible displays, lab-on-a-chip diagnostics, wearable devices, medical testing, smart implants and biometric technology. “Los Alamos (Los Alamos), a physicist and first author specializing in semiconductor nanocrystals, announced the new results on October 1
For decades, microelectronics technology has been made of ultra-high purity silicon processed in a specially created clean room environment. Recently, silicon-based microelectronics has been challenged by a variety of alternative technologies that allow the manufacture of complex electronic circuits outside the clean room through inexpensive, easily available chemical techniques. Colloidal semiconductor nanoparticles made by chemical methods in a less stringent environment are such an emerging technology. Due to their small size and unique properties directly controlled by quantum mechanics, these particles are called quantum dots.
Colloidal quantum dots consist of a semiconductor core covered with organic molecules. Because of this hybrid property, they combine the easy-to-understand advantages of traditional semiconductors with the chemical versatility of molecular systems. These characteristics are attractive for the realization of a new type of flexible electronic circuit, which can be printed on almost any surface, including plastic, paper and even human skin. This feature can benefit many areas, including consumer electronics, security, digital signage, and medical diagnosis.
The key element of an electronic circuit is the transistor, which acts as a switch for a current activated by an applied voltage. Generally, transistors are divided into pairs of n-type and p-type devices to control the flow of negative and positive charges, respectively. Such complementary transistor pairs are the cornerstone of modern CMOS (Complementary Metal Oxide Semiconductor) technology, which enables microprocessors, memory chips, image sensors, and other electronic devices.
The first quantum dot transistor was demonstrated about twenty years ago. However, integrating complementary n-type and p-type devices in the same quantum dot layer is still a long-term challenge. In addition, most of the efforts in this field have focused on nanocrystals based on lead and cadmium. These elements are highly toxic heavy metals, which greatly limit the practicality of the demonstration equipment.
The team of Los Alamos researchers and their collaborators from the University of California, Irvine, proved that by using copper indium selenide (CuInSe2) heavy metal-free quantum dots, they can solve the toxicity problem and achieve direct integration of n- and p transistors at the same time Located in the same quantum dot layer. To prove the practicality of the developed method, they created functional circuits that perform logical operations.
The innovative technology proposed by Klimov and colleagues in their new paper allows them to define p-type and n-type transistors by applying two different types of metal contacts (gold and indium, respectively). They completed the device by depositing a layer of common quantum dots on top of pre-patterned contacts. Klimov said: “This method can directly integrate any number of complementary p-type and n-type transistors into the same quantum dot layer, which can be made into a continuous, unpatterned film by standard spin coating.”
Colloidal quantum dot laser diodes are just around the corner
Hyeong Jin Yun et al., a solution processable integrated CMOS circuit based on colloidal CuInSe2 quantum dots, Nature Communications (2020). DOI: 10.1038 / s41467-020-18932-5
Provided by Los Alamos National Laboratory
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