Self-Powered Photodetector Breakthrough Just Unveiled
Researchers at KAIST, led by Professor Kayoung Lee from the School of Electrical Engineering, have developed a groundbreaking self-powered photodetector. This cutting-edge sensor boasts the highest sensitivity among its peers, operating without the need for an external power source when exposed to light. This innovation could revolutionize wearable technology, biosignal monitoring, and Internet of Things (IoT) applications.
The team tackled a significant hurdle in semiconductor technology with this advancement. Conventional silicon-based photodetectors suffer from low light responsivity, while two-dimensional semiconductors like MoS2 (molybdenum disulfide) are so thin that they traditionally require a challenging doping process to adjust their electrical properties. This doping often compromises the material's structure and performance.
Professor Lee's team circumvented these limitations by designing a novel PN junction structure that generates electrical signals independently when exposed to light. They achieved this by using a van der Waals bottom electrode, which enhances the semiconductor's sensitivity without altering its structure through doping.
A PN junction is a fundamental component in semiconductors, formed by joining p-type (positive) and n-type (negative) materials. This structure allows current to flow in one direction under light exposure, crucial for photodetectors and solar cells. The team's innovative approach involved a partial gate structure, which applies an electrical signal to only part of the semiconductor. This mimics the behavior of a traditional PN junction without the need for doping.
The gentle attachment of the van der Waals electrode preserves the semiconductor's lattice integrity while ensuring effective signal transfer. As a result, the new device achieves remarkable light detection sensitivity, surpassing 21 A/W. This sensitivity is over 20 times greater than that of existing powered sensors and significantly exceeds that of other self-powered MoS2 sensors.
Professor Lee expressed excitement about their achievement, noting that it surpasses the capabilities of traditional silicon sensors. She highlighted the technology's potential in miniaturizing and powering next-generation electronic devices, including smartphones.
This pioneering work, co-authored by Ph.D. candidates Jaeha Hwang and Jungi Song, was published in the esteemed journal Advanced Functional Materials. It received support from organizations such as the National Research Foundation of Korea and Samsung Electronics.