References of "Marso, Michel 50002313"
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See detailTowards future III-nitride based THz OEICs in the UV range
Fox, Alfred; Mikulics, Martin; Winden, Andreas et al

in ASDAM 2012, The Ninth International Conference on Advanced Semiconductor Devices and Microsystems (2012)

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See detailTuning the spectral sensitivity of vertical InN nanopyramid based photodetectors by means of band gap engineering and/or nanostructure size control
Trellenkamp, Stefan; Mikulics, Martin; Winden, Andreas et al

in ASDAM 2012, The Ninth International Conference on Advanced Semiconductor Devices and Microsystems (2012)

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See detailElectrical and structural characterization of AlGaN/GaN field-effect transistors with recessed gate
Mikulics, Martin; Fox, Alfred; Marso, Michel UL et al

in Vacuum (2012), 86(6), 754-756

Performance of AlGaN/GaN heterostructure field-effect transistors (HFETs) with recessed gate was investigated and compared with non-recessed counterparts. Optimal dry etch conditions by plasma assisted Ar ... [more ▼]

Performance of AlGaN/GaN heterostructure field-effect transistors (HFETs) with recessed gate was investigated and compared with non-recessed counterparts. Optimal dry etch conditions by plasma assisted Ar sputtering were found for ~6 nm gate recess of a 20 nm thick AlGaN barrier layer. A decrease of the residual strain after the gate recessing (from -0.9 GPa to -0.68 GPa) was evaluated from the photoluminescence measurement. The saturation drain current at the gate voltage VG = 1 V decreased from 1.05 A/mm to 0.85 A/mm after the recessing. The gate voltage for a maximal transconductance (240-250 mS/mm) has shifted from -3 V for non-recessed HFETs to -0.2 V for recessed counterparts. Similarly, the threshold voltage increased after the gate recessing. A decrease of the sheet charge density from 1 x 10 13 cm-2 to4 x 10 12 cm-2 at VG = 0 V has been evaluated from the capacitance measurements. The RF measurements yielded a slight increase of the cut-off frequencies after the gate recessing. All these indicate that the gate recessing is a useful tool to optimize the AlGaN/GaN HFET performance for high-frequency applications as well as for the preparation of normally-off devices. [less ▲]

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See detailResidual strain in recessed AlGaN/GaN heterostructure field-effect transistors evaluated by micro photoluminescence measurements
Mikulics, Martin; Hardtdegen, Hilde; Winden, Andreas et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2012), 9(3-4), 911-914

The residual strain in AlGaN/GaN heterostructure field-effect transistors (HFETs) with recessed gates and their non-recessed counterparts were investigated by micro photoluminescence measurements (μ-PL ... [more ▼]

The residual strain in AlGaN/GaN heterostructure field-effect transistors (HFETs) with recessed gates and their non-recessed counterparts were investigated by micro photoluminescence measurements (μ-PL). It is found that strain relaxation accounts for the observed sheet carrier density reduction after gate recessing. The usefulness of the method for device processing optimization is demonstrated. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. [less ▲]

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See detailGaAs nanowhiskers for femtosecond photodetectors and THz emitters
Mikulics, Martin; Zhang, J.; Sobolewski, Roman et al

in ASDAM 2012, The Ninth International Conference on Advanced Semiconductor Devices and Microsystems (2012)

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See detailImproving output power of terahertz heterodyne photomixer by impedance matching
Juul, Lars UL; Mikulics, Martin; Marso, Michel UL

in ASDAM 2012, The Ninth International Conference on Advanced Semiconductor Devices and Microsystems (2012)

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See detailMonolithic Integration of Ultrafast Photodetector and MESFET in the GaN Material System
Mikulics, M.; Kordoš, P.; Gregušová, D. et al

in IEEE Photonics Technology Letters (2011), 23(17), 1189-1191

We have fabricated and characterized ultrafast metal–semiconductor–metal (MSM) photodetectors integrated with metal–semiconductor–field-effect-transistors (MESFETs) integrated in coplanar strip lines in ... [more ▼]

We have fabricated and characterized ultrafast metal–semiconductor–metal (MSM) photodetectors integrated with metal–semiconductor–field-effect-transistors (MESFETs) integrated in coplanar strip lines in the GaN/AlN/SiC material system. We recorded electrical transients of the single photodetector as short as 0.9 ps wide by optoelectric pump–probe measurements using 360-nm-wavelength and 100-fs-duration laser pulses. Electric photoresponse transients of the photodetector with 6-mV peak amplitude were amplified by the MESFET, resulting in 4-ps-wide and 35-mV peak amplitude signals. This monolithically integrated optoelectronic circuit is presented as a potential candidate for high-speed ultraviolet optoelectronics [less ▲]

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See detailGaN for THz Sources
Marso, Michel UL

in Proceedings of SPIE, vol. 7945, pp. 79450Y-1 - 79450Y-9 (2011)

In this work we investigate two different approaches to generate THz radiation by the use of the unique electrical and thermal properties of GaN. One method is heterodyne photomixing, a compact and ... [more ▼]

In this work we investigate two different approaches to generate THz radiation by the use of the unique electrical and thermal properties of GaN. One method is heterodyne photomixing, a compact and inexpensive approach to generate continuous electromagnetic radiation in the terahertz range, with tuneable frequency. It uses two lasers with slightly different wavelengths that illuminate an ultrafast photoconductor. The interference of both laser beams generates a beat frequency of the illumination intensity in the terahertz range. One drawback of the conventionally used LT GaAs as ultrafast photoconductor material is the relatively low THz power in the nW to ?W range. The aim of our work is to increase the output power by replacing the LT GaAs with GaN. This semiconductor is rather known as basic material for blue LEDs and lasers, but it has also remarkable electrical and thermal properties that allow higher laser power and bias voltage. A more conventional, electronic approach to generate THz radiation consists in the fabrication of an oscillator circuit based on ultrafast transistors, e.g. Hetero Field Effect Transistors based on InGaAs. These circuits can be designed up to about 100 GHz oscillation frequency. The THz region is achieved by frequency multipliers, e.g. realized by very small-sized Schottky diodes. However, each multiplier stage considerable reduces the output power. In this field we investigate GaN based transistor devices to profit from the much better power performance of this material, compared to classical semiconductors. Devices in this material system are usually used for high power applications at moderate frequencies, but the very high electron saturation velocity of GaN allows the application above 100 GHz as well. [less ▲]

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See detailGaN for THz Sources
Marso, Michel UL

in Proceedings of the Eighth International Conference on Advanced Semiconductor Devices and Microsystems ASDAM 2010 (2010)

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See detailComparison of AlGaN/GaN HFETs and MOSHFETs in prospect of oscillator design
Fox, Alfred; Mikulics, Martin; Strang, B. et al

in The Eighth International Conference on Advanced Semiconductor Devices and Microsystems, ASDAM 2010 (2010)

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See detailQuantum transport in narrow-gap semiconductor nanocolumns
Lüth, Hans; Blömers, Christian; Richter, Thomas et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2010), 7(2), 386-389

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See detailFemtosecond and highly sensitive GaAs metal–semiconductor–metal photodetectors grown on aluminum mirrors/pseudo-substrates,
Mikulics, Martin; Adam, Roman; Sofer, Zdenek et al

in Semiconductor Science & Technology (2010), 25(7), 75001

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See detailSpatially resolved measurements of depletion properties of large gate two-dimensional electron gas semiconductor terahertz modulators
Kleine-Ostmann, T.; Pierz, K.; Hein, G. et al

in Journal of Applied Physics (2009), 105(9), 093707-1-093707-6

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See detailDas Spektrum der elektromagnetischen Strahlung: Technische Nutzung und Herausforderungen
Marso, Michel UL

in Revue Technique Luxembourgeoise (2009), (4), 36-37

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See detailOutput Power Improvement in MSM Photomixers by Modified Finger Contacts Configuration
Mikulics, M.; Marso, Michel UL; Lepsa, Mike et al

in IEEE Photonics Technology Letters (2009), 21(3), 146-148

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See detailFinite element simulation of metal-semiconductor-metal photodetector
Guarino, G.; Donaldson, W. R.; Mikulics, Martin et al

in Solid-State Electronics (2009), 53(10), 1144-1148

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See detailSensitivity enhancement of metal-semiconductor-metal photodetectors on low-temperature-grown GaAs using alloyed contacts
Mikulics, M. UL; Marso, Michel UL; Wu, S. et al

in IEEE Photonics Technology Letters (2008), 20(12), 1054-1056

We have fabricated and characterized metal–semiconductor–metal (MSM) photodetectors based on lowtemperature-grown GaAs with alloyed (i.e., ohmic-type) contacts. The annealed contacts optimize the electric ... [more ▼]

We have fabricated and characterized metal–semiconductor–metal (MSM) photodetectors based on lowtemperature-grown GaAs with alloyed (i.e., ohmic-type) contacts. The annealed contacts optimize the electric field distribution inside the photodetector structure which results in an up-to-200% responsivity increase of the devices, compared to conventional MSM detectors with standard nonalloyed (Schottky-type) metallization fabricated on identical material. The improved MSM device with alloyed contacts shows more than three times larger output amplitude at illumination with a 100-fs Ti : sapphire laser, compared to the nonalloyed devices, without degradation of detector speed. [less ▲]

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See detailInvestigation on Localized States in GaN Nanowires
Polenta, L. UL; Rossi, M.; Cavallini, Anna et al

in ACS Nano (2008), 2

GaN nanowires with diameters ranging between 50 and 500 nm were investigated by electrical and photoinduced current techniques to determine the influence of their size on the opto-electronic behavior of ... [more ▼]

GaN nanowires with diameters ranging between 50 and 500 nm were investigated by electrical and photoinduced current techniques to determine the influence of their size on the opto-electronic behavior of nanodevices. The conductivity, photoconductivity, and persistent photoconductivity behavior of GaN nanowires are observed to strongly depend on the wire diameter. In particular, by spectral photoconductivity measurements, three main sub-band-gap optoelectronic transitions were detected, ascribed to the localized states giving rise to the characteristic blue, green, and yellow bands of GaN. Photoconductivity with below-band-gap excitation varies orders of magnitude with the wire diameter, similarly to that observed for near-band-edge excitation. Moreover, yellow-band-related signal shows a superlinear behavior with respect to the band-edge signal, offering new information for the modeling of the carrier recombination mechanism along the nanowires. The photoconductivity results agree well with a model which takes into account a uniform distribution of the localized states inside the wire and their direct recombination with the electrons in the conduction band. [less ▲]

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See detailPhase-coherent transport in InN nanowires of various sizes
Blömers, Ch UL; Schäpers, T.; Richter, T. UL et al

in Physical Review (2008), B 77(20),

We investigate phase-coherent transport in InN nanowires of various diameters and lengths. The nanowires were grown by means of plasma-assisted molecular beam epitaxy. Information on the phase-coherent ... [more ▼]

We investigate phase-coherent transport in InN nanowires of various diameters and lengths. The nanowires were grown by means of plasma-assisted molecular beam epitaxy. Information on the phase-coherent transport is gained by analyzing the characteristic fluctuation pattern in the magnetoconductance. For a magnetic field oriented parallel to the wire axis, we found that the correlation field mainly depends on the wire cross section, while the fluctuation amplitude is governed by the wire length. In contrast, if the magnetic field is perpendicularly oriented, for wires longer than approximately 200 nm, the correlation field is limited by the phase coherence length. Further insight into the orientation dependence of the correlation field is gained by measuring the conductance fluctuations at various tilt angles of the magnetic field. [less ▲]

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See detailAcoustic charge transport in GaN nanowires
Ebbecke, J.; Maisch, S.; Wixforth, A. et al

in Nanotechnology (2008), 19(27), 275708-5

We present acoustic charge transport in GaN nanowires (GaN NWs). The GaN NWs were grown by molecular beam epitaxy (MBE) on silicon(111) substrates. The nanowires were removed from the silicon substrate ... [more ▼]

We present acoustic charge transport in GaN nanowires (GaN NWs). The GaN NWs were grown by molecular beam epitaxy (MBE) on silicon(111) substrates. The nanowires were removed from the silicon substrate, aligned using surface acoustic waves (SAWs) on the piezoelectric substrate LiNbO3 and finally contacted by electron beam lithography. Then, a SAW was used to create an acoustoelectric current in the GaN NWs which was detected as a function of radio-frequency (RF) wave frequency and its power. The presented method and our experimental findings open up a route towards new acoustic charge transport nanostructuredevices in a wide bandgap material such as GaN. [less ▲]

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