Violet phosphorus (VP) is an emerging layered semiconductor that could expand the material palette for future electronic and optoelectronic devices. But before it can be used reliably, scientists need to answer a basic question: how does charge naturally move through it?
A research team led by Kwanpyo Kim from the Department of Physics at Yonsei University, in collaboration with researchers at Ewha Womans University, has now clarified the intrinsic electrical behavior of VP by building high-quality field-effect transistors that protect the material from processing damage and environmental degradation. The study was published as a Just Accepted manuscript in Nano Research on May 22, 2026.
Violet phosphorus, also known as type-V red phosphorus, is one of several solid forms of elemental phosphorus. Its layered structure and semiconducting properties have attracted attention for nanoscale electronics and light-sensitive devices. Previous studies, however, reported conflicting behavior, with some devices appearing p-type and others n-type. The uncertainty has made it difficult to assess the true potential of VP as a transistor channel material.
The challenge is partly practical. Like many layered semiconductors, VP can be sensitive to air, moisture and device processing. Direct metal deposition and imperfect interfaces can introduce defects, obscure intrinsic behavior and increase contact resistance. To avoid these problems, the team assembled van der Waals heterostructure devices in a nitrogen-filled glovebox, fully encapsulated the VP channel with hexagonal boron nitride, and used damage-free contact strategies based on graphite contacts or pre-patterned metal bottom electrodes.
The resulting devices showed robust unipolar n-type conduction, meaning that electrons serve as the dominant charge carriers. The current increased systematically under positive gate voltage, and the devices showed ohmic-like contact behavior in the low-bias regime. The team also found that the n-type behavior persisted when different contact materials, including graphite, gold (Au) and platinum (Pt), were used.
“Previous reports left open a fundamental question about whether violet phosphorus should be considered a p-type or n-type semiconductor,” said Kwanpyo Kim, corresponding author of the study. “By protecting the channel and engineering clean interfaces, we could observe robust n-type transport and separate the material’s intrinsic behavior from artifacts introduced during device fabrication.”
The devices achieved current on/off ratios approaching 10⁷ and maintained stable performance after long-term exposure to ambient conditions for more than 200 days. Dual-gate and temperature-dependent measurements further supported the conclusion that the violet phosphorus channel exhibits clear n-type behavior.
The team also demonstrated that carrier transport could be tuned by gate and drain bias. Depending on the applied bias, the devices could be operated from a rectifying Schottky-diode-like regime to a more symmetric ohmic-like regime, suggesting potential for multifunctional device operation.
“For two-dimensional and layered semiconductors, interface quality often determines whether we can see the true physics of the material,” said Jae Joon Kim, first author of the paper. “Our work provides a device platform for studying VP more reliably and for exploring its use in future electronic and optoelectronic systems.”
Other contributors include Joonho Kim, Dong-gyu Kim, Uje Choi, Jieun Yeon and Jinsub Park from Yonsei University; and Seoyoung Lim and Dong-Wook Kim from Ewha Womans University and the Institute for Multiscale Matter and Systems.
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2025-00560649), the Global Learning & Academic Research Institution for Masters, PhD students, and Postdocs (G-LAMP) Program of the National Research Foundation of Korea, funded by the Ministry of Education (RS-2024-00442483), and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT & MOE) (RS-2025-16063688).
DOI Link:
https://doi.org/10.26599/NR.2026.94908865
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.
Nano Research
22-May-2026