Browsing by Author "Chang, P."

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Epitaxial stabilization of a monoclinic phase in Y(2)O(3) films on c-plane GaN
(2011-05-15)
Chang, W. H.
;
Chang, P.
;
Lee, W. C.
;
Lai, T. Y.
;
Kwo, J.
Nanometer-thick Y(2)O(3) films were grown epitaxially on GaN (0 0 0 1) using molecular beam epitaxy (MBE). The structures of the oxide films were studied in situ by reflection high energy electron diffraction (RHEED) during the growth and ex situ by high resolution X-ray diffraction using synchrotron radiation. At atmospheric pressure. Y(2)O(3) exists in either cubic or hexagonal structure. For the first time, the high-pressure monoclinic phase of Y(2)O(3), stabilized by epitaxy, was prepared and preserved under atmospheric pressure. The electrical characterization carried out on the Y(2)O(3)/GaN metal-oxide-semiconductor (MOS) capacitors showed a leakage current density of similar to 3.3 x 10(-6) A/cm(2) at 1.5 MV/cm, which remained almost the same after 800 degrees C annealing. A dielectric constant of similar to 20 and a hysteresis of similar to 250 mV were deduced from the capacitance-voltage (C-V) curves for the epitaxial monoclinic Y(2)O(3). (C) 2010 Elsevier B.V. All rights reserved.
Epitaxial stabilization of a monoclinic phase in Y2O3 films on c-plane GaN
(2011-05-15)
Chang, W. H.
;
Chang, P.
;
Lee, W. C.
;
Lai, T. Y.
;
Kwo, J.
Nanometer-thick Y2O3 films were grown epitaxially on GaN (0 0 0 1) using molecular beam epitaxy (MBE). The structures of the oxide films were studied in situ by reflection high energy electron diffraction (RHEED) during the growth and ex situ by high resolution X-ray diffraction using synchrotron radiation. At atmospheric pressure. Y2O3 exists in either cubic or hexagonal structure. For the first time, the high-pressure monoclinic phase of Y2O3, stabilized by epitaxy, was prepared and preserved under atmospheric pressure. The electrical characterization carried out on the Y2O3/GaN metal-oxide-semiconductor (MOS) capacitors showed a leakage current density of similar to 3.3 x 10(-6) A/cm(2) at 1.5 MV/cm, which remained almost the same after 800 degrees C annealing. A dielectric constant of similar to 20 and a hysteresis of similar to 250 mV were deduced from the capacitance-voltage (C-V) curves for the epitaxial monoclinic Y2O3. (C) 2010 Elsevier B.V. All rights reserved.
MBE-Enabling technology beyond Si CMOS
(2011-05-15)
Chang, P.
;
Lee, W. C.
;
Lin, T. D.
;
Hsu, C. H.
;
Kwo, J.
Achievement of low interfacial densities of states, small equivalent oxide thickness, high kappa values, and thermal stability at high temperatures in the high kappa dielectrics on high carrier mobility semiconductors, the leading candidates for technology beyond Si CMOS, has been made using MBE. This paper reviews our recent advances in meeting the unprecedented demands in materials and physics for the new technology. Moreover, self-aligned inversion-channel InGaAs and Ge MOSFETs using MBE-Ga(2)O(3)(Gd(2)O(3)) as the gate dielectric are compared favorably with those using the gate dielectrics made from other thin film techniques. (C) 2010 Elsevier B.V. All rights reserved.
Structural Characteristics of Nanometer Thick Gd(2)O(3) Films Grown on GaN (0001)
(2010-12-01)
Chang, W. H.
;
Chang, P.
;
Lai, T. Y.
;
Lee, Y. J.
;
Kwo, J.
High-quality Gd(2)O(3) epi-films 5-20 nm thick have been grown on GaN (0001) using molecular beam epitaxy A detailed structural investigation was carried out by in situ reflection high energy electron diffraction cross sectional transmission electron microscopy, and X-ray scattering using a synchrotron radiation source The films consist of the high temperature monoclinic (m) phase with six rotational domains which can be easily mistaken for being the hexagonal phase All the domains follow the m-Gd(2)O(3) ((2) over bar 01)< 020 > parallel to GaN (0001) < 11<(2)over bar>0 > orientational relationship
Structural Characteristics of Nanometer Thick Gd2O3 Films Grown on GaN (0001)
(2010-12-01)
Chang, W. H.
;
Chang, P.
;
Lai, T. Y.
;
Lee, Y. J.
;
Kwo, J.
High-quality Gd2O3 epi-films 5-20 nm thick have been grown on GaN (0001) using molecular beam epitaxy A detailed structural investigation was carried out by in situ reflection high energy electron diffraction cross sectional transmission electron microscopy, and X-ray scattering using a synchrotron radiation source The films consist of the high temperature monoclinic (m) phase with six rotational domains which can be easily mistaken for being the hexagonal phase All the domains follow the m-Gd2O3 ((2) over bar 01)< 020 > parallel to GaN (0001) < 11<(2)over bar>0 > orientational relationship
Structure of HfO2 films epitaxially grown on GaAs(001)
(2006-09-18)
Hsu, C. -H.
;
Chang, P.
;
Lee, W. C.
;
Yang, Z. K.
;
Lee, Y. J.
High-quality HfO2 films of technologically important thickness ranging from 1.8 to 17 nm have been grown epitaxially on GaAs (001) by molecular beam epitaxy. Thorough structural and morphological investigations were carried out by x-ray scattering and high-resolution transmission electron microscopy. The films exhibit an atomically sharp interface with the substrate and are of a monoclinic phase with predominant (001)-plane epitaxy between the HfO2 films and GaAs, in spite of a large lattice mismatch of > 8.5%.