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Hasselt, Belgium

Everts J.,Kath University Leuven Kuleuven | Das J.,IMEC | Van Den Keybus J.,TRIPHASE | Genoe J.,IMEC | And 3 more authors.
2010 IEEE Energy Conversion Congress and Exposition, ECCE 2010 - Proceedings | Year: 2010

A boost converter was constructed using a high voltage enhancement mode (E-mode) AlGaN/GaN/AlGaN DHFET transistor grown on Si<111>. The very low dynamic onresistance (R dyn ≈ 0:23 Ω) and very low gate-charges (e.g. Q gate≈ 15 nC at V DS = 200 V) result in minor transistor losses. Together with a proper design of the passive components and the use of SiC diodes, very high overall efficiencies are reached. Measurements show high conversion efficiencies of 96.1% (P out = 106 W, 76 to 142 V at 512.5 kHz) and 93.9% (P out = 97:5 W, 78 to 142 V at 845.2 kHz). These are, to our knowledge, the highest efficiencies reported for an enhancement mode GaN DHFET on Si in this frequency range. The transistor switching losses are concentrated in the turn-on interval, and dominate at high frequencies. This is due to a limited positive gate-voltage swing, as the gate-source diode restricts the positive drive voltage. © 2010 IEEE. Source


Epigan Inc. | Entity website

Company EpiGaN focuses on delivering world-leading III-nitride epitaxial material per our customers specifications, enabling them to develop innovative products. As a pure play epi material supplier, EpiGaN offers a clear business model, ideal to build long-term customer relationships


Epigan Inc. | Entity website

Custom EpiGaN offers customed GaN III-Nitride epi wafers upon request. We can vary the AlGaN layers, the buffer layers and the substrate to meet your specific needs in the areas of HV power, RF and sensors ...


Cheng K.,IMEC | Leys M.,IMEC | Degroote S.,Epigan Inc. | Bender H.,IMEC | And 3 more authors.
Journal of Crystal Growth | Year: 2012

In this paper we present a study of the relaxation mechanism of the top Al 0.30Ga 0.70N layer grown on GaN, as used in High Electron Mobility Transistor (HEMT) structures. We show that the initial mechanism for relaxation of strain is by means of formation of V-grooves on the surface of the Al 0.30Ga 0.70N. It is also demonstrated that a thin Si 3N 4 layer, grown in-situ, immediately after the Al xGa 1-xN can freeze-in the surface structure. Using tapping mode Atomic Force Microscopy (AFM) it can be observed that immediately after termination of the growth of the thin Al 0.30Ga 0.70N layer, the steps on the surface show round shape and spiral-like features. After about 1 min of annealing time under NH 3 flow the surface structures become straighter. Upon prolonged annealing a V-groove pattern is observed. These V-grooves run along the 〈-1-120〉 directions. Although some other facets can be observed, from cross-sectional Transmission Electron Microscopy (TEM) images we can infer that the side walls of the grooves are {1-101} planes and that the grooves do not penetrate till the Al 0.30Ga 0.70N/GaN interface. Therefore, we come to the conclusion that the initial relaxation of a thin Al 0.30Ga 0.70N layer does not occur via a dislocation glide mechanism leading to the formation of an array of misfit dislocations at the Al 0.30Ga s.70N/GaN interface. Instead, we propose that the mechanism is by surface instability leading to V-groove formation. © 2012 Elsevier B.V. All rights reserved. Source


Capriotti M.,Vienna University of Technology | Alexewicz A.,Vienna University of Technology | Fleury C.,Vienna University of Technology | Gavagnin M.,Vienna University of Technology | And 7 more authors.
Applied Physics Letters | Year: 2014

Using a generalized extraction method, the fixed charge density N int at the interface between in situ deposited SiN and 5 nm thick AlGaN barrier is evaluated by measurements of threshold voltage Vth of an AlGaN/GaN metal insulator semiconductor high electron mobility transistor as a function of SiN thickness. The thickness of the originally deposited 50 nm thick SiN layer is reduced by dry etching. The extracted Ni nt is in the order of the AlGaN polarization charge density. The total removal of the in situ SiN cap leads to a complete depletion of the channel region resulting in Vth = +1 V. Fabrication of a gate stack with Al2O3 as a second cap layer, deposited on top of the in situ SiN, is not introducing additional fixed charges at the SiN/Al2O3 interface. © 2014 AIP Publishing LLC. Source

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