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Scanning probe microscopy (STM, AFM & SNOM); Nanostructured materials; Surfaces and interfaces; Thin film growth.
Present Research Activities:
Driven by the present trend of device miniaturization and emerging opportunities of molecular electronics, high-precision measurement on surface properties and atomic-scale manipulation of materials are increasingly required. Because when the device dimensions decrease to the point where a single molecular layer may represent a significant percentage of the device scales, surface and interface effects (surface stress and relaxation, morphological and structural irregularites, concentration of unsaturated bonds, and atomic-intermixing, etc.) can significantly influence device properties, understanding surface reactions and the ordering of atoms or molecules are thus highly desirable. The research of my group is centered on using scanning tunneling microscopy/spectroscopy (STM/STS), atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM) to characterize structural, electronic and optical properties of surfaces and interfaces at atomic / molecular / nanometer scale. The research activities are twofold: (1) To investigate semiconductor hetero-epitaxy, the aim is to understand the elementary processes during the hetero-growth and the controlled surface/interface quantum feature formations; (2) To investigate organic ultra-thin film growth on silicon-based substrates, and to characterize electron transport and other exceptional properties of the thin films. The aim is to couple existing microelectronics technology with organic-based structures for seeking its potential applications in the next generation of electronic devices.
Supported by NSERC, CFI/OIT, MMO and the University of Guelph.
X.R. Qin, B.S. Swartzentruber and M.G. Lagally (2000), Diffusional kinetics of SiGe dimers on Si(100) using atom-tracking scanning tunneling microscopy, Phys. Rev. Lett. 85, 3660-3663.
X.R. Qin, B.S. Swartzentruber and M.G. Lagally (2000), Scanning tunneling microscopy identification of atomic-scale intermixing on Si(100) at submonolayer Ge coverages, Phys. Rev. Lett. 84, 4546-4549.
X.R. Qin and M.G. Lagally (1999), View of the empty states of the Si(100)-2x1 surface via scanning tunneling microscopy imaging at very low biases, Phys. Rev. B 59, 7293-7296.
X.R. Qin, F. Liu, B.S. Swartzentruber and M.G. Lagally (1998), Modification of Si(100) substrate bonding by adsorbed Ge or Si dimer islands, Phys. Rev. Lett. 81, 2288-2291.
X.R. Qin and M.G. Lagally (1997), Adatom Pairing Structures for Ge on Si(100): The Initial Stage of Island Formation, Science 278,1444-1447.
X.R. Qin and P.R. Norton (1996), Scanning tunneling microscopy of the phase transition between H/Si(100)-(2x1) and H/Si(100)-(3x1), Phys. Rev. B 53, 11100-11107.