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“Mechanism for Ohmic contact formation on Si3N4 passivated AlGaN/GaN high-electron-mobility transistors”. Van Daele B, Van Tendeloo G, Derluyn J, Shrivastava P, Lorenz A, Leys MR, Germain M;, Applied physics letters 89, Artn 201908 (2006). http://doi.org/10.1063/1.2388889
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 15
DOI: 10.1063/1.2388889
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“Thermal characterization of polycrystalline diamond thin film heat spreaders grown on GaN HEMTs”. Zhou Y, Ramaneti R, Anaya J, Korneychuk S, Derluyn J, Sun H, Pomeroy J, Verbeeck J, Haenen K, Kuball M, Applied physics letters 111, 041901 (2017). http://doi.org/10.1063/1.4995407
Abstract: Polycrystalline diamond (PCD) was grown onto high-k dielectric passivated AlGaN/GaN-on-Si high electron mobility transistor (HEMT) structures, with film thicknesses ranging from 155 to 1000 nm. Transient thermoreflectance results were combined with device thermal simulations to investigate the heat spreading benefit of the diamond layer. The observed thermal conductivity (k(Dia)) of PCD films is one-to-two orders of magnitude lower than that of bulk PCD and exhibits a strong layer thickness dependence, which is attributed to the grain size evolution. The films exhibit a weak temperature dependence of k(Dia) in the measured 25-225 degrees C range. Device simulation using the experimental jDia and thermal boundary resistance values predicts at best a 15% reduction in peak temperature when the source-drain opening of a passivated AlGaN/GaN-on-Si HEMT is overgrown with PCD. Published by AIP Publishing.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 78
DOI: 10.1063/1.4995407
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“Exploring possibilities of band gap measurement with off-axis EELS in TEM”. Korneychuk S, Partoens B, Guzzinati G, Ramaneti R, Derluyn J, Haenen K, Verbeeck J, Ultramicroscopy 189, 76 (2018). http://doi.org/10.1016/J.ULTRAMIC.2018.03.021
Abstract: A technique to measure the band gap of dielectric materials with high refractive index by means of energy electron loss spectroscopy (EELS) is presented. The technique relies on the use of a circular (Bessel) aperture and suppresses Cherenkov losses and surface-guided light modes by enforcing a momentum transfer selection. The technique also strongly suppresses the elastic zero loss peak, making the acquisition, interpretation and signal to noise ratio of low loss spectra considerably better, especially for excitations in the first few eV of the EELS spectrum. Simulations of the low loss inelastic electron scattering probabilities demonstrate the beneficial influence of the Bessel aperture in this setup even for high accelerating voltages. The importance of selecting the optimal experimental convergence and collection angles is highlighted. The effect of the created off-axis acquisition conditions on the selection of the transitions from valence to conduction bands is discussed in detail on a simplified isotropic two band model. This opens the opportunity for deliberately selecting certain transitions by carefully tuning the microscope parameters. The suggested approach is experimentally demonstrated and provides good signal to noise ratio and interpretable band gap signals on reference samples of diamond, GaN and AlN while offering spatial resolution in the nm range. (C) 2018 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 2.843
Times cited: 7
DOI: 10.1016/J.ULTRAMIC.2018.03.021
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“Flat GaN epitaxial layers grown on Si(111) by metalorganic vapor phase epitaxy using step-graded AlGaN intermediate layers”. Cheng K, Leys M, Degroote S, van Daele B, Boeykens S, Derluyn J, Germain M, Van Tendeloo G, Engelen J, Borghs G, Journal of electronic materials 35, 592 (2006). http://doi.org/10.1007/s11664-006-0105-1
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 1.579
Times cited: 102
DOI: 10.1007/s11664-006-0105-1
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“The role of Al on Ohmic contact formation on n-type GaN and AlGaN/GaN”. van Daele B, Van Tendeloo G, Ruythooren W, Derluyn J, Leys M, Germain M, Applied physics letters 87, 061905 (2005). http://doi.org/10.1063/1.2008361
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.411
Times cited: 57
DOI: 10.1063/1.2008361
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“Transmission electron microscopy characterisation of Ti and Al/Ti contacts on GaN and AlGaN/GaN”. van Daele B, Van Tendeloo G, Ruythooren W, Derluyn J, Leys MR, Germain M, Springer proceedings in physics 107, 389 (2005)
Abstract: Transmission electron microscopy has been applied to study Ti and Al/Ti contacts on GaN and AlGaN/GaN as a function of annealing temperature. This has lead to a profound understanding of the role of Al, both in the contact formation on n-GaN and on AlGaN/GaN. Al in the AlGaN decreases the N-extraction by Ti out of the nitride, because of the strong Al-N bond. Al in the metal bilayer also reduces the N-extraction by Ti due to a preferential alloy mixing.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
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