Monolayer Nucleation and Passivation of Advanced Electronic Materials

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Technical Description: Atomic layer deposition is a cyclic chemical process that provides sub-nanometer control of layer thickness. The bonding of the first layer is the critical step in providing a low defect interface, which enables nucleation of atomic layer deposition within each unit cell. The project is developing an atomic layer understanding of oxide monolayers deposited on two very different semiconducting materials, gallium nitride and graphene, by combining scanning tunneling microscopy and scanning tunneling spectroscopy. These materials have surfaces with very low chemical reactivity, enabling the fabrication of unique electronics devices; however, these materials lack reactive atoms that can strongly bond to atomic layer deposition precursors. For graphene, the non-reactive surface is functionalized via adsorption of an ordered monolayer of organic coordination complexes while for gallium nitride and order layer of inorganic function groups are deposited. Two techniques are developed with broad applicability: (a) ultra high vacuum cross-sectional Kelvin Probe Force Microscopy to image the electrostatic potentials inside working capacitors and field effect transistors on the nanoscale and (b) contactless ultra high vacuum variable frequency capacitance-voltage for in-situ measurement of gate oxide defects.Non-technical Description: At present, computer chip speed and performance are limited by the dissipation of heat. Further increases in performance require decreasing in the supply voltage to stabilize heat dissipation per unit area. This research project seeks to develop the monolayer chemistry required for nucleating layer by layer growth of the nanoscale insulators, which will enable lower-power computing or more efficient high power communication. The project includes activities designed to recruit and support under-represented minority PhD students and undergraduate students who are interested in materials science and engineering or materials chemistry.