Browsing by Author "Brennan, Barry"
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Item Accumulation Capacitance Frequency Dispersion of Ⅲ-Ⅴ Metal-Insulator-Semiconductor Devices due to Disorder Induced Gap States(American Institute of Physics Inc., 2014-07-07) Galatage, R. V.; Zhernokletov, Dmitry M.; Dong, Hong; Brennan, Barry; Hinkle, Christopher L.; Wallace, Robert M.; Vogel, E. M.The origin of the anomalous frequency dispersion in accumulation capacitance of metal-insulator-semiconductor devices on InGaAs and InP substrates is investigated using modeling, electrical characterization, and chemical characterization. A comparison of the border trap model and the disorder induced gap state model for frequency dispersion is performed. The fitting of both models to experimental data indicate that the defects responsible for the measured dispersion are within approximately 0.8nm of the surface of the crystalline semiconductor. The correlation between the spectroscopically detected bonding states at the dielectric/III-V interface, the interfacial defect density determined using capacitance-voltage, and modeled capacitance-voltage response strongly suggests that these defects are associated with the disruption of the III-V atomic bonding and not border traps associated with bonding defects within the high-k dielectric.Item Chemical and Electrical Characterization of the HfO2/InAlAs InterfaceBrennan, Barry; Galatage, Rohit V.; Thomas, K.; Pelucchi, E.; Hurley, P. K.; Kim, Jiyoung; Hinkle, Christopher L.; Vogel, E. M.; Wallace, Robert M.InAlAs has the potential to be used as a barrier layer in buried channel quantum well field effect transistor devices due to favorable lattice-matching and carrier confinement properties with InGaAs. Field effect device structures of this nature may also require a high-k oxide deposited on the InAlAs surface to reduce leakage current. This study investigates the impact of surface preparations and atomic layer deposition of HfO2 on these surfaces using x-ray photoelectron spectroscopy to analyse the chemical interactions taking place, as well as the electrical performance of associated capacitor devices. A large concentration of As related surface features is observed at the InAlAs surface, and is attributed to a large Dit response in electrical measurements.Item GaSb Oxide Thermal Stability Studied by Dynamic-XPS(AVS: Science & Technology of Materials, Interfaces, and Processing) McDonnell, Steven; Brennan, Barry; Bursa, Emin; Wallace, Robert M.; Winkler, K.; Baumann, P.The thermal decomposition of the native GaSb oxides is studied using time resolved x-ray photoelectron spectroscopy with a temperature resolution of better than 1 K. The expected transfer of oxygen from Sb-O to Ga-O before the eventual desorption of all oxides is observed. However, an initial reaction resulting in the reduction of Sb₂O₃ along with the concurrent increase in both Ga₂O₃ and Sb₂O₄ is detected in the temperature range of 450-525 K. Using the relative changes in atomic concentrations of the chemical species observed; the initial reaction pathway is proposed.Item In situ atomic layer deposition half cycle study of Al2O 3 growth on AlGaN(American Institute of Physics, 2012-11-10) Brennan, Barry; Qin, Xiaoye; Dong, Hong; Kim, Jiyoung; Wallace, Robert M.; 70133685 (Kim, J)Use the DOI address to see the article abstract. A subscription or fee may be necessary to view the article.Item In Situ Study of E-Beam Al And Hf Metal Deposition on Native Oxide InP (100)Dong, Hong; Santosh, KC; Azcatl, Angelica; Cabrera, Wilfredo; Qin, Xiaoye; Brennan, Barry; Zhernokletov, Dmitry; Cho, Kyeongjie; Wallace, Robert M.The interfacial chemistry of thin Al (∼3 nm) and Hf (∼2 nm) metal films deposited by electron beam (e-beam) evaporation on native oxide InP (100) samples at room temperature and after annealing has been studied by in situ angle resolved X-ray photoelectron spectroscopy and low energy ion scattering spectroscopy. The In-oxides are completely scavenged forming In-In/In-(Al/Hf) bonding after Al and Hf metal deposition. The P-oxide concentration is significantly decreased, and the P-oxide chemical states have been changed to more P-rich oxides upon metal deposition. Indium diffusion through these metals before and after annealing at 250 °C has also been characterized. First principles calculation shows that In has lower surface formation energy compared with Al and Hf metals, which is consistent with the observed indium diffusion behavior.Item In Situ Study of the Role of Substrate Temperature during Atomic Layer Deposition of HfO2 on InP(2013-10-16) Dong, Hong; Santosh, KC; Qin, Xiaoye; Brennan, Barry; McDonnell, Steven; Zhernokletov, Dmitry; Hinkle, Christopher L.; Kim, Jiyoung; Cho, Kyeongjie; Wallace, Robert M.; 70133685 (Kim, J)The dependence of the "self cleaning" effect of the substrate oxides on substrate temperature during atomic layer deposition (ALD) of HfO₂ on various chemically treated and native oxide InP (100) substrates is investigated using in situ X-ray photoelectron spectroscopy. The removal of In-oxide is found to be more efficient at higher ALD temperatures. The P oxidation states on native oxide and acid etched samples are seen to change, with the total P-oxide concentration remaining constant, after 10 cycles of ALD HfO₂ at different temperatures. An (NH₄)₂ S treatment is seen to effectively remove native oxides and passivate the InP surfaces independent of substrate temperature studied (200°C, 250°C and 300°C) before and after the ALD process. Density functional theory modeling provides insight into the mechanism of the changes in the P-oxide chemical states.Item Investigation of Arsenic and Antimony Capping Layers, and Half Cycle Reactions During Atomic Layer Deposition of Al₂O₃ on GaSb(100)Zhernokletov, Dmitry M.; Dong, Hong; Brennan, Barry; Kim, Jiyoung; Wallace, Robert M.; Yakimov, M.; Tokranov, V.; Oktyabrsky, S.; 70133685 (Kim, J)In-situ monochromatic x-ray photoelectron spectroscopy, low energy electron diffraction, ion scattering spectroscopy, and transmission electron microscopy are used to examine the GaSb(100) surfaces grown by molecular beam epitaxy after thermal desorption of a protective As or Sb layer and subsequent atomic layer deposition (ALD) of Al₂O₃. An antimony protective layer is found to be more favorable compared to an arsenic capping layer as it prevents As alloys from forming with the GaSb substrate. The evolution of oxide free GaSb/Al₂O₃ interface is investigated by "half-cycle" ALD reactions of trimethyl aluminum and deionized water.