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Gong, Xian

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Gong, Xian

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2016 - 201942020 - 20211

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Author's Publications: search.filters.isAuthorOfPublication.dfc247f7-03b8-4fac-a5e4-7f81c3283d40

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    Epitaxial Growth of MgxCa1–xO on GaN by Atomic Layer Deposition
    (American Chemical Society (ACS), 2016) Lou, Xiabing; Zhou, Hong; Kim, Sang Bok; Alghamdi, Sami; Gong, Xian; Feng, Jun; Wang, Xinwei; Ye, Peide D.; Gordon, Roy
    We demonstrate for the first time that a singlecrystalline epitaxial MgxCa1−xO film can be deposited on gallium nitride (GaN) by atomic layer deposition (ALD). By adjusting the ratio between the amounts of Mg and Ca in the film, a lattice matched MgxCa1−xO/GaN(0001) interface can be achieved with low interfacial defect density. High-resolution X-ray diffraction (XRD) shows that the lattice parameter of this ternary oxide nearly obeys Vegard’s law. An atomically sharp interface from cross-sectional transmission electron microscopy (TEM) confirmed the high quality of the epitaxy.High-temperature capacitance−voltage characterization showed that the film with composition Mg0.25Ca0.75O has the lowest interfacial defect density. With this optimal oxide composition, a Mg0.25Ca0.75O/AlGaN/GaN metal−oxide −semiconductor high-electron-mobility (MOS-HEMT) device was fabricated. An ultrahigh on/off ratio of 1012 and a near ideal SS of 62 mV/dec were achieved with this device.
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    Vapor Deposition of Copper-Manganese Interconnects
    (IEEE, 2016) Gordon, Roy; Feng, Jun; Li, Kecheng; Gong, Xian
    Chemical vapor deposition (CVD) of copper and manganese can produce interconnects scaled down to below 10 nm, while enhancing their conductivity and lifetime. CVD using similar super-conformal processes can enable very narrow through-silicon-vias, as well as tiny and robust flexible wires between chips. Silica insulating layers can be made by a super-conformal and rapid atomic layer deposition (ALD) process.
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    Direct-Liquid-Evaporation Chemical Vapor Deposition of Nanocrystalline Cobalt Metal for Nanoscale Copper Interconnect Encapsulation
    (American Chemical Society (ACS), 2017) Feng, Jun; Gong, Xian; Lou, Xiabing; Gordon, Roy
    In advanced microelectronics, precise design of liner and capping layers become critical, especially when it comes to the fabrication of Cu interconnects with dimensions lower than its mean free path. Herein, we demonstrate that direct-liquid-evaporation chemical vapor deposition (DLECVD) of Co is a promising method to make liner and capping layers for nanoscale Cu interconnects. DLE-CVD makes pure, smooth, nanocrystalline, and highly conformal Co films with highly controllable growth characteristics. This process allows full Co encapsulation of nanoscale Cu interconnects, thus stabilizing Cu against diffusion and electromigration. Electrical measurements and high-resolution elemental imaging studies show that the DLE-CVD Co encapsulation layer can improve the reliability and thermal stability of Cu interconnects. Also, with the high conductivity of Co, the DLE-CVD Co encapsulation layer have the potential to further decrease the power consumption of nanoscale Cu interconnects, paving the way for Cu interconnects with higher efficiency in future high-end microelectronics.
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    ALD Growth of MgxCa1xO on GaN and Its Band Offset Analysis
    (American Chemical Society (ACS), 2021-02-08) Gong, Xian; Lou, Xiabing; Kim, Sang Bok; Gordon, Roy
    Atomic layer deposition (ALD) processes were developed for growing MgO and CaO on GaN substrates using a home-built ALD reactor with amidinate-based precursors. An optimal deposition condition was then determined to deposit pure MgxCa1–xO by tuning deposition temperature, achieving a high-quality film without carbon and hydroxyl contamination. Band offset analysis was conducted by X-ray photoelectron spectroscopy on MgxCa1–xO/GaN samples with various compositions. Mg0.25Ca0.75O/GaN demonstrated band alignments between defect-free and fully pinned, while other ratios showed near fully pinned alignments, which agree with the best electrical properties achieved in our previous studies. This result indicates that band offset analysis provides a good aid in understanding part of the electrical and interfacial properties for oxide/semiconductor structures.
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    Synthesis of Volatile, Reactive Coinage Metal 5,5-Bicyclic Amidinates With Enhanced Thermal Stability for Chemical Vapor Deposition
    (Royal Society of Chemistry (RSC), 2019) Tong, Liuchuan; Gong, Xian; Feng, Jun; Gordon, Roy; Davis, Luke; Beth, Eugene
    Many microelectronic devices require thin films of silver or gold as wiring layers. We report silver(I) and gold(I) bicyclic amidinate complexes, wherein the constrained ligand geometry lessens the propensity for thermal decomposition. These new volatile compounds provide metallic films of silver and gold during CVD with hydrogen below 230 °C.