Ulsan National Institute of Science and Technology · Materials Science
Professor Joonki Suh's research lab specializes in the synthesis, characterization, and application of two-dimensional (2D) van der Waals materials and heterostructures, with a focus on manipulating their electronic, optical, and thermoelectric properties through defect engineering, doping, and heterostructure integration. The lab explores scalable growth techniques—particularly atomic layer deposition—for wafer-scale, annealing-free fabrication of 2D semiconductors and tellurium films, enabling practical nanoelectronic and spintronic devices. A key research direction involves controlling native defects and dopants to tune carrier concentration and transport, with applications in high-performance transistors, p-n junctions, and neuromorphic computing hardware. The lab also investigates topological insulators and their unique 2D electron gas states, aiming to unravel fundamental defect physics and enable advanced device functionalities.
Figures are computed from collected data and may differ slightly.
Layered transition metal dichalcogenides (TMDs) draw much attention as the key semiconducting material for two-dimensional electrical, optoelectronic, and spintronic devices. For most of these applications, both n- and p-type materials are needed to form junctions and support bipolar carrier conduction. However, typically only one type of doping is stable for a particular TMD. For example, molybdenum disulfide (MoS2) is natively an n-type presumably due to omnipresent electron-donating sulfur va
Doping of traditional semiconductors has enabled technological applications in modern electronics by tailoring their chemical, optical and electronic properties. However, substitutional doping in two-dimensional semiconductors is at a comparatively early stage, and the resultant effects are less explored. In this work, we report unusual effects of degenerate doping with Nb on structural, electronic and optical characteristics of MoS<sub>2</sub> crystals. The doping readily induces a structural t
Simultaneous increases in electrical conductivity (up to 200%) and thermopower (up to 70%) are demonstrated by introducing native defects in Bi2 Te3 films, leading to a high power factor of 3.4 × 10(-3) W m(-1) K(-2). The maximum enhancement of the power factor occurs when the native defects act beneficially both as electron donors and energy filters to mobile electrons. They also act as effective phonon scatterers.
Two-dimensional materials and their heterostructures have thus far been identified as leading candidates for nanoelectronics owing to the near-atom thickness, superior electrostatic control, and adjustable device architecture. These characteristics are indeed advantageous for neuro-inspired computing hardware where precise programming is strongly required. However, its successful demonstration fully utilizing all of the given benefits remains to be further developed. Herein, we present van der W
Two-dimensional electron gas (2DEG) coexists with topological states on the surface of topological insulators (TIs), while the origin of the 2DEG remains elusive. In this work, electron density in TI thin films (${\text{Bi}}_{2}$${\text{Se}}_{3}$, ${\text{Bi}}_{2}$${\text{Te}}_{3}$, and their alloys) were manipulated by controlling the density of electronically active native defects with particle irradiation. The measured electron concentration increases with irradiation dose but saturates at di
Scalable production and integration techniques for van der Waals (vdW) layered materials are vital for their implementation in next-generation nanoelectronics. Among available approaches, perhaps the most well-received is atomic layer deposition (ALD) due to its self-limiting layer-by-layer growth mode. However, ALD-grown vdW materials generally require high processing temperatures and/or additional postdeposition annealing steps for crystallization. Also, the collection of ALD-producible vdW ma
Phase-change memory (PCM), a non-volatile memory technology, is considered the most promising candidate for storage class memory and neuro-inspired devices. It is generally fabricated based on GeTe–Sb2Te3 pseudo-binary alloys. However, natively, it has technical limitations, such as noise and drift in electrical resistance and high current in operation for real-world device applications. Recently, heterogeneously structured PCMs (HET-PCMs), where phase-change materials are hetero-assembled with
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