Browsing by Author "Han, J"

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    Liquid-metal-assisted deposition and patterning of molybdenum dioxide at low temperature
    (American Chemical Society, 2021-11-10) Wang, Y; Mayyas, M; Yang, J; Ghasemian, MB; Tang, J; Mousavi, M; Han, J; Ahmed, M; Baharfar, M; Mao, G; Yao, Y; Esrafilzadeh, D; Cortie, DL; Kalantar-Zadeh, K
    Molybdenum dioxide (MoO2), considering its nearmetallic conductivity and surface plasmonic properties, is a great material for electronics, energy storage devices and biosensing. Yet to this day, room-temperature synthesis of large area MoO2, which allows deposition on arbitrary substrates, has remained a challenge. Due to their reactive interfaces and specific solubility conditions, gallium-based liquid metal alloys offer unique opportunities for synthesizing materials that can meet these challenges. Herein, a substrate-independent liquid metal-based method for the room temperature deposition and patterning of MoO2 is presented. By introducing a molybdate precursor to the surrounding of a eutectic gallium-indium alloy droplet, a uniform layer of hydrated molybdenum oxide (H2MoO3) is formed at the interface. This layer is then exfoliated and transferred onto a desired substrate. Utilizing the transferred H2MoO3 layer, a laser-writing technique is developed which selectively transforms this H2MoO3 into crystalline MoO2 and produces electrically conductive MoO2 patterns at room temperature. The electrical conductivity and plasmonic properties of the MoO2 are analyzed and demonstrated. The presented metal oxide room-temperature deposition and patterning method can find many applications in optoelectronics, sensing, and energy industries. © 2021 American Chemical Society
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    SIMS investigation of oxygen in 3C-SiC on Si
    (IEEE, 2008-07-28) Han, J; Dimitrijev, S; Kong, F; Tanner, P; Atanacio, AJ
    In this paper, we present and analyse secondary ion mass spectrometry (SIMS) measurements of oxygen concentration in 3C-SiC epitaxial layers on Si. The concentration of oxygen determined by SIMS was as high as 10 19 to 10 20 atom/cm 3 . Unlike silicon, oxygen can act as donor atoms in SiC with calculated ionization levels of 200 meV. It is generally believed that the main contribution of dopant concentration in the unintentionally doped SiC film is related to background nitrogen. Because of the high ionisation level, oxygen is not electrically active at room temperature. By measuring the conductivity of the films at higher temperatures, we extracted three donor energy levels: E A1 =79 meV, E A2 = 180 meV, and E A3 = 350 meV. The activation energy of 180 meV could be associated with the calculated ionization level for oxygen. Further analysis of the conductivity measurements at elevated temperatures will be performed to determine the electrically active donor concentration that is associated with the activation energy of 180 meV. © Copyright 2008 IEEE
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    SIMS investigation on the 3C-SiC on Si
    (David Publishing Company, 2009-08-01) Han, J; Dimitrijev, S; Kong, F; Atanacio, AJ
    In this paper, the spectrometry (SIMS) measurements of oxygen concentration in 3C SiC epitaxial layers on Si were presented and analysed. The concentration of oxygen determined by SIMS was as high as 1019 to 1020 atom/cm3. Unlike silicon, oxygen can act as donor atoms in SiC with calculated ionization levels of 200 meV [1-2]. It is generally believed that the main contribution of dopant concentration in the unintentionally doped SiC film is related to background nitrogen. Because of the high ionisation level, oxygen is not electrically active at room temperature. By measuring the conductivity of the films at higher temperatures, we extracted three donor energy levels: EA1= 79 meV, EA2= 180 meV, and EA3= 350 meV. The activation energy of 180 meV could be associated with the calculated ionization level for oxygen. Further analysis of the conductivity measurements at elevated temperatures will be performed to determine the electrically active donor concentration that is associated with the activation energy of 180 meV. © 2009 David Publishing Company