Browsing by Author "Macwan, Isaac"

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    Structural and band alignment properties of Al2O3 on epitaxial Ge grown on (100), (110), and (111)A GaAs substrates by molecular beam epitaxy
    Hudait, Mantu K.; Zhu, Yizheng; Maurya, Deepam; Priya, Shashank; Patra, Prabir K.; Ma, Anson W. K.; Aphale, Ashish; Macwan, Isaac (American Institute of Physics, 2013-04-07)
    Structural and band alignment properties of atomic layer Al2O3 oxide film deposited on crystallographically oriented epitaxial Ge grown in-situ on (100), (110), and (111)A GaAs substrates using two separate molecular beam epitaxy chambers were investigated using cross-sectional transmission microscopy (TEM) and x-ray photoelectron spectroscopy (XPS). High-resolution triple axis x-ray measurement demonstrated pseudomorphic and high-quality Ge epitaxial layer on crystallographically oriented GaAs substrates. The cross-sectional TEM exhibited a sharp interface between the Ge epilayer and each orientation of the GaAs substrate as well as the Al2O3 film and the Ge epilayer. The extracted valence band offset, Delta E-v, values of Al2O3 relative to (100), (110), and (111) Ge orientations using XPS measurement were 3.17 eV, 3.34 eV, and 3.10 eV, respectively. Using XPS data, variations in Delta E-v related to the crystallographic orientation were Delta E-V(110)Ge > Delta E-V(100) Ge >= Delta E-V(111)Ge and the conduction band offset, Delta E-c, related to the crystallographic orientation was Delta E-c(111)Ge > Delta E-c(110)Ge > Delta E-c(100)Ge using the measured Delta E-v, bandgap of Al2O3 in each orientation, and well-known Ge bandgap of 0.67 eV. These band offset parameters are important for future application of Ge-based p- and n-channel metal-oxide field-effect transistor design. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4799367]