Publications

Showing 187 results for Author: Kai Xiao

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Sep, 2026

Conference Paper

Temperature-Dependent Transport Characteristics of 2D MoS2 Channel FETs Grown Using Salt-Based Precursors

D Transition Metal Dichalcogenides (TMDs), particularly MoS2, are promising candidates for sub-10 nm Gate All Around (GAA) CMOS FETs. Salt-assisted Chemical Vapor Deposition (CVD) enable lateral MoS2 growth at atmospheric pressure and low temperatures. This work analyzes salt-based precursor-driven CVD-grown MoS2 FETs at various temperatures. MoS2 was grown using Ammonium…
Jul, 2026

Journal

Spontaneous Polarization Suppression of Exciton–Exciton Annihilation in Rhombohedral-Stacked Bilayer Molybdenum Disulfide

Rapid exciton–exciton annihilation (EEA) in two-dimensional semiconductors limits access to high-density excitonic regimes essential for efficient optoelectronic operation under strong excitation. Here, we show that EEA is strongly suppressed in rhombohedral (3R)-stacked MoS2 bilayers relative to nonpolar 2H bilayers, and that this suppression is quantitatively consistent…
Jun, 2026

Journal

Twist-Angle-Dependent Excitons in Moiré MoTe2 Visualized by Cryogenic STEM and Monochromated EELS

van der Waals twisted bilayers of transition-metal dichalcogenides exhibit diverse excitonic phenomena arising from moiré superlattices and lattice reconstruction. While interlayer strain and relaxation reshape their electronic bands, their nanoscale influence on the excitonic fine structure remains poorly understood. Here, we study the interplay between spin–orbit couplin…
Jun, 2026

Journal

Autonomous fabrication of tailored defect structures in 2D materials using machine learning-enabled scanning transmission electron microscopy

Materials with desired quantum properties can be engineered from atomic scale assembly techniques, but existing methods often lack the agility and accuracy to precisely and intelligently control the manufacturing process. Here we demonstrate a fully autonomous approach to fabricating atomic-level defects using electron beams in scanning transmission electron microscopy (ST…
May, 2026

Journal

Controllable Thin-Film Approaches for Doping and Alloying Transition Metal Dichalcogenides Monolayers

Two-dimensional (2D) transition metal dichalcogenide (TMD) monolayers exhibit exciting properties and versatile material chemistry promising for device miniaturization, energy, quantum information science, and flexible optoelectronics. Their outstanding structural stability permits a variety of foreign dopants that can modulate their optical and electronic properties and i…
May, 2026

Journal

Ultrafast exciton and trion dynamics in highly 𝑛-doped Mo⁢S2 monolayers: Many-body effects

Understanding many-body interactions of excitons and charge carriers in monolayer semiconductors is crucial for tuning their unique optical properties and optimizing their performance in optoelectronic devices. However, the sensitivity of these atomically-thin semiconductors to doping, defects, and strain – arising from synthesis, substrate, and environmental conditions –…
Mar, 2026

Journal

Substrate-Directed Underlayer Growth of Bilayer MoS2 Revealed by Mo Isotope Labeling

Direct control over the vertical formation sequence and stacking registry in van der Waals (vdW) bilayers is essential for device performance and moiré engineering yet difficult to resolve unambiguously with conventional probes. We use Mo isotope labeling in a two-step chemical vapor deposition process to synthesize bilayer MoS2 and trace its vertical formation on common s…
Feb, 2026

Journal

Your Clean Graphene is Still Not Clean

Researchers working with thin samples, such as monolayer graphene, are consistently struggling against contamination. Indeed, the problem of hydrocarbon contamination is known from the earliest days of electron microscopy and efforts to reduce this problem are ubiquitous to almost all high-vacuum experiments. Accurate knowledge of the behavior of such contamination is esse…
Dec, 2025

Journal

Nonequilibrium Synthesis of TiO2 Nanoparticle “Building Blocks” for Crystal Growth by Sequential Attachment in Pulsed Laser Deposition

Nonequilibrium growth pathways for crystalline nanostructures with metastable phases are demonstrated through the gas-phase formation, attachment, and crystallization of ultrasmall amorphous nanoparticles as building blocks in pulsed laser deposition (PLD). Temporally and spatially resolved gated-intensified charge couple device (ICCD) imaging and ion probe measurements ar…
Dec, 2025

Journal

Defect Engineering in Large-Scale CVD-Grown Hexagonal Boron Nitride: Formation, Spectroscopy, and Spin Relaxation Dynamics

Recently, numerous techniques have been reported for generating optically active defects in exfoliated hexagonal boron nitride (hBN), which hold transformative potential for quantum photonic devices. However, achieving on-demand generation of desirable defect types in scalable hBN films remains a significant challenge. Here, it is demonstrated that formation of negative bo…
Nov, 2025

Journal

Encapsulation of monolayer 2D materials using kinetic energy-controlled pulsed laser deposition

The integration of monolayer (ML) two-dimensional (2D) materials into next-generation microelectronics, optoelectronics, and sensors is hindered by their sensitivity to environmental exposure. Deposition of additional layers for encapsulation or growth on ML 2D materials by versatile but energetic plasma techniques such as pulsed laser deposition (PLD) has not been conside…
Sep, 2025

Journal

Interfacial Momentum Matching for Ohmic Van Der Waals Contact Construction

The difficulty of achieving ohmic contacts is a long-standing challenge for the development and integration of devices based on 2D materials, due to the large mismatch between their electronic properties and those of both traditional metal-based and van der Waals (vdWs) electrodes. Research has focused primarily on the electronic energy band alignment, while the effects of…

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Publications

Temperature-Dependent Transport Characteristics of 2D MoS2 Channel FETs Grown Using Salt-Based Precursors

Spontaneous Polarization Suppression of Exciton–Exciton Annihilation in Rhombohedral-Stacked Bilayer Molybdenum Disulfide

Twist-Angle-Dependent Excitons in Moiré MoTe2 Visualized by Cryogenic STEM and Monochromated EELS

Autonomous fabrication of tailored defect structures in 2D materials using machine learning-enabled scanning transmission electron microscopy

Controllable Thin-Film Approaches for Doping and Alloying Transition Metal Dichalcogenides Monolayers

Ultrafast exciton and trion dynamics in highly 𝑛-doped Mo⁢S2 monolayers: Many-body effects

Substrate-Directed Underlayer Growth of Bilayer MoS2 Revealed by Mo Isotope Labeling

Your Clean Graphene is Still Not Clean

Nonequilibrium Synthesis of TiO2 Nanoparticle “Building Blocks” for Crystal Growth by Sequential Attachment in Pulsed Laser Deposition

Defect Engineering in Large-Scale CVD-Grown Hexagonal Boron Nitride: Formation, Spectroscopy, and Spin Relaxation Dynamics

Encapsulation of monolayer 2D materials using kinetic energy-controlled pulsed laser deposition

Interfacial Momentum Matching for Ohmic Van Der Waals Contact Construction