Hasselt, Belgium
Hasselt, Belgium
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Schuller T.A.,University of Bristol | Kuball M.,University of Bristol | Flower S.E.,University of Bath | James T.D.,University of Bath | And 8 more authors.
Sensors and Actuators, B: Chemical | Year: 2011

We demonstrate a novel field-effect saccharide sensor device using an AlGaN/GaN heterostructure functionalized with a chemical receptor, featuring a thiol group, alkane chain linker and a simple boronic acid. Fabricated devices were demonstrated to electronically detect buffered saccharide solutions (fructose, galactose and glucose) of varying concentrations. These results provide proof-of-concept for the development AlGaN/GaN-based sensor devices incorporating boronic acid receptor chemistry. © 2011 Elsevier B.V. All rights reserved.

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.

Herbecq N.,Institute of Electronic | Roch-Jeune I.,Institute of Electronic | Rolland N.,Institute of Electronic | Visalli D.,Epigan Inc. | And 4 more authors.
Applied Physics Express | Year: 2014

We demonstrate a high-voltage low on-resistance AlN/GaN/AlGaN double heterostructure grown by metal-organic chemical vapor deposition on a silicon (111) substrate using a total buffer thickness of less than 2 μm. A fully scalable local substrate removal technique was developed to dramatically enhance the off-state breakdown voltage of the transistors. The three-terminal breakdown voltage of these devices using a gate-drain distance of 15μm increased significantly, from 750V to 1.9 kV, after local substrate removal. The high two-dimensional electron gas carrier density (2.3 × 1013cm-2) associated with the low sheet resistance enables a record combination of a specific on-resistance (1.6mOcm2) and high breakdown voltage for GaN-on-Si transistors. © 2014 The Japan Society of Applied Physics.

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.

Knetzger M.,Fraunhofer Institute for Integrated Systems and Device Technology | Meissner E.,Fraunhofer Institute for Integrated Systems and Device Technology | Derluyn J.,Epigan Inc. | Germain M.,Epigan Inc. | Friedrich J.,Fraunhofer Institute for Integrated Systems and Device Technology
Solid State Phenomena | Year: 2016

The influence of structural defects in the active layer of GaN-on-Si substrates on the vertical leakage current was studied. The structural defects were analyzed by analytical scanning electron microscopy by means of cathodoluminescence (CL). The leakage current was determined by vertical I-V measurements. Two possibilities were found, which give potential explanations for the variations of the vertical leakage current: i) Threading dislocations, which may partially form leakage paths, were detected by CL imaging. ii) Variations of the carbon doping, which is used to tune GaN to a semi insulating material were revealed by CL spectroscopy. © (2016) Trans Tech Publications, Switzerland.

Zhang L.,Catholic University of Leuven | Zhang L.,IMEC | Cheng K.,IMEC | Degroote S.,Epigan Inc. | And 4 more authors.
Journal of Applied Physics | Year: 2010

For practical applications, it is important to control strain by carefully tuning growth conditions for stress modification. Strain can have a pronounced impact on device behavior and is caused by extrinsic thermal stress and a tunable intrinsic growth stress. The impact of strain on GaN epilayers was investigated by photoluminescence and high resolution x-ray diffraction (XRD). The GaN samples were grown by metal organic vapor phase epitaxy, on sapphire, 4H-SiC, freestanding GaN and Si (111) substrates. Both free and bound exciton transitions were observed at low temperature, and their energy shift was analyzed with respect to the strain values derived from XRD. We also characterized the valence band split and the GaN bandgap as a function of the strain at 4 K. © 2010 American Institute of Physics.

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.

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

Sensors EpiGaN provides state-of-the-art GaN epitaxial layers deposited on 3, 4 and 6inch SiC-substrates or 3, 4, 6 inch and 200mm HR Si-substrates for sensor applications. New MEMS and sensor applications are using GaN-on-Si epi material for CO, NO2, strain, pressure and optical sensing ...

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