A technology for manufacturing high-performance p-type semiconductor devices based on two-dimensional materials has been developed, and it is expected that it will be practically applicable to the next-generation complementary metal-oxide-semiconductor (CMOS) industry to which ultra-fine technology will be applied.

UNIST (President Yong-Hoon Lee) announced on the 24th that the research team of Professor Soon-Yong Kwon from the Graduate School of Semiconductor Materials and Components and the Department of New Materials Engineering, together with the research team of Professor Jong-Hoon Lee from UNIST, succeeded in producing a high-performance p-type semiconductor device using molybdenum telluride compound semiconductor (MoTe2).

CMOS is a device in which p-type semiconductors and n-type semiconductors are complementarily joined. It is a semiconductor device with low power consumption and is widely used in everyday electronic devices such as PCs and smartphones. CMOS made of silicon is mainly used, and p-type and n-type semiconductor devices can be implemented through a process of injecting ions.

Two-dimensional materials are gaining attention as next-generation semiconductors, but because they are very thin, their structures are easily destroyed during the same process. In particular, two-dimensional materials have the problem of various defects occurring at the interface when forming a general three-dimensional metal electrode. Various studies have been conducted to solve this problem, but most of the research is focused on ‘n-type semiconductors.’

The research team, on the other hand, utilized molybdenum telluride compound semiconductor (MoTe2) among the 'p-type semiconductors'. They developed a technology that can synthesize devices on a large area of 4 inches through chemical vapor deposition (CVD), which creates a thin film through a chemical reaction. Based on the developed technology, they produced a high-performance p-type transistor by utilizing the fact that the work function is controlled when a three-dimensional metal is deposited on a two-dimensional semi-metal.

By controlling the synthesis temperature and time, a 4-inch sized semiconductor thin film was synthesized with high purity. After transferring a semiconductor seed that helps the phase transition to a semi-metallic thin film and synthesizing it at a low temperature below 500 degrees, it was confirmed that a high-quality semiconductor was formed in the crystal shape of the seed.

First author Jang So-ra, a researcher in the combined master’s and doctoral program, explained, “The device manufacturing method developed in this study can be applied not only to the two-dimensional semiconductor presented in the paper, but also to various two-dimensional materials.” She added, “We hope that the developed two-dimensional material will be applied to the CMOS industry and contribute to improved integration.”

This study was participated by UNIST Professor Kwon Soon-yong (Graduate School of Semiconductor Materials and Components/Department of Materials Science and Engineering, co-corresponding author), Professor Lee Jong-hoon (Department of Materials Science and Engineering, co-corresponding author), Dr. Song Seung-wook (co-first author, currently at the University of Pennsylvania, USA), Dr. Yoon A-ram (co-first author), and graduate student Jang So-ra (co-first author).