References of "Marso, Michel 50002313"
     in
Bookmark and Share    
Full Text
See detailAn optimization of terahertz local oscillators based on LT-GaAs technology
Mayorga, I. C.; Mikulics, M.; Schmitz, A. et al

in SPIE - The International Society for Optical Engineering (2004), 5498 (2004)

Detailed reference viewed: 52 (0 UL)
Full Text
See detailLarge-area traveling-wave LT-GaAs photomixers for LO application
Michael, E. A.; Mikulics, M.; Marso, Michel UL et al

in SPIE - The International Society for Optical Engineering (2004), 5498 (2004)

Detailed reference viewed: 62 (0 UL)
Full Text
Peer Reviewed
See detailImpact of layer structure on performance of unpassivated AlGaN/GaN/SiC HEMTs,
Bernát, J.; Wolter, M.; Fox, A. et al

in Electronics Letters (2004), 40(1), 78-80

The performance of unpassivated AlGaN=GaN=SiC HEMTs prepared on different MOVPE grown layer structures is reported. An overall improvement of device characteristics using doped structures in comparison to ... [more ▼]

The performance of unpassivated AlGaN=GaN=SiC HEMTs prepared on different MOVPE grown layer structures is reported. An overall improvement of device characteristics using doped structures in comparison to undoped counterpart is observed. This can be demonstrated by IDS of 0.86 and 1.33 A=mm, gm of 220 and 273 mS=mm, fT of 33 and 43 GHz and fmax of 54 and 61 GHz for 0.3 mm gate length devices on undoped and doped structures, respectively. The DC=pulsed I–V characteristics as well as power measurements show insignificant RF dispersion of HEMTs on doped structures. These results underline the advantage of doped layer structures for preparation of high-performance AlGaN=GaN HEMTs. [less ▲]

Detailed reference viewed: 51 (0 UL)
Full Text
See detailGaN Nanocolumns on Si(111) Grown b Molecular Beam Epitaxy
Calarco, Raffaella; Marso, Michel UL; Meijers, R. et al

in Proc. 5th Intern. Conf. Advanced Semicon. Dev. & Microsystems ASDAM’04 (2004)

GaN nanocolumns are reproducibly grown by plasma-assisted molecular beam epitaxy on Si(111). The nanocolumn density and diameter, 20–150 nm, are controlled by means of the III/V ratio. The nanocolumns ... [more ▼]

GaN nanocolumns are reproducibly grown by plasma-assisted molecular beam epitaxy on Si(111). The nanocolumn density and diameter, 20–150 nm, are controlled by means of the III/V ratio. The nanocolumns grow parallel to the [111] direction of the Si substrate. The columns have been transferred to a Si(100) substrate covered with a layer of 300nm SiO2; single nanowire devices have been fabricated using finger shaped electrical contacts (Ti/Au) obtained by e-beam patterning technique. The electrical transport properties of the resulting metal–semiconductor–metal nanostructures are analyzed by means of current– voltage measurements with and without UV-illumination. [less ▲]

Detailed reference viewed: 23 (0 UL)
Full Text
See detailFabrication and performance of hybrid photoconductive devices based on freestanding LT-GaAs, Ultrafast Phenomena in Semiconductors and Nanostructure Materials VIII,
Adam, R.; Mikulics, M.; Wu, S. et al

in Proceedings of SPIE (2004), 5353 (2004)

We report on fabrication and high-frequency performance of our photodetectors and photomixers based on freestanding low-temperature-grown GaAs (LT-GaAs). In our experiments, the LT-GaAs/AlAs bilayers were ... [more ▼]

We report on fabrication and high-frequency performance of our photodetectors and photomixers based on freestanding low-temperature-grown GaAs (LT-GaAs). In our experiments, the LT-GaAs/AlAs bilayers were grown on 2-inch diameter, semi-insulating GaAs wafers by a molecular beam epitaxy. Next, the bilayer was patterned to form 10 × 10 μm2 to 150 × 150 μm2 structures using photolithography and ion beam etching. The AlAs layer was then selectively etched in diluted HF solution, and the LT-GaAs device was lifted from its substrate and transferred on top of a variety of substrates including Si, MgO/YBaCuO, Al2O3, and a plastic foil. Following the transfer, metallic coplanar transmission lines were fabricated on top of the LT-GaAs structure, forming a metal semiconductor-metal photodetectors or photomixer structures. Our freestanding devices exhibited above 200 V breakdown voltages and dark currents at 100 V below 3×10-7 A. Device photoresponse was measured using an electro-optic sampling technique with 100-fs-wide laser pulses at wavelengths of 810 nm and 405 nm as the excitation source. For 810-nm excitation, we measured 0.55 ps-wide electrical transients with voltage amplitudes of up to 1.3 V. The signal amplitude was a linear function of the applied voltage bias, as well as a linear function of the laser excitation power, below well-defined saturation thresholds. Output power from the freestanding photomixers was measured with two beam laser illumination experimental setup. Reported fabrication technique is suitable for the LT-GaAs integration with a range of semiconducting, superconducting, and organic materials for high-frequency hybrid optoelectronic applications. [less ▲]

Detailed reference viewed: 44 (0 UL)
Full Text
See detailMSM varactor diodes based on AlGaN/GaN/SiC HEMT layer structures
Marso, Michel UL; Bernát, J.; Javorka, P. et al

in Proc. 5th Intern. Conf. Advanced Semicon. Dev. & Microsystems ASDAM’04 (2004)

The influence of a carrier supply layer on the electrical properties of MSM diodes based on AlGaN/GaN HEMT layer structures is investigated. The voltage dependence of the Schottky contact capacitance ... [more ▼]

The influence of a carrier supply layer on the electrical properties of MSM diodes based on AlGaN/GaN HEMT layer structures is investigated. The voltage dependence of the Schottky contact capacitance allows the use of the device as varactor diode with CMAX / CMIN ratios up to 17, tuneable by contact geometry. The carrier supply doping determines the sheet carrier density of the twodimensional electron gas channel, which is responsible for the transition voltage and the series resistance of the MSM diode. A device based on the highest doped layer structure shows a cutoff frequency as high as 65 GHz. [less ▲]

Detailed reference viewed: 75 (0 UL)
Full Text
Peer Reviewed
See detailA novel two-color photodetector based on an InAlAs-InGaAs HEMT layer structure
Marso, Michel UL; Wolter, M.; Kordoš, P.

in IEEE Photonics Technology Letters (2004), 16 (2004)(11), 2541-2543

The spectral responsivity of an InAlAs–InGaAs metal–semiconductor–metal diode above a two-dimensional electron gas (2DEG) is investigated as a function of the applied bias. At low voltages, only the ... [more ▼]

The spectral responsivity of an InAlAs–InGaAs metal–semiconductor–metal diode above a two-dimensional electron gas (2DEG) is investigated as a function of the applied bias. At low voltages, only the InAlAs layer above the 2DEG contributes to the photocurrent, while the InGaAs channel layer is activated at higher bias. This results in a voltage-dependent spectral response of the photodetector. The ratio of the responsivities at 1300 and 850 nm changes from 0.03- at 1-V to 0.44- at 1.6-V bias. This property makes the device a candidate suitable to detect and to separate optical information originated both from the GaAs (850 nm) and in the InGaAs (1300, 1550 nm)-based optoelectronic technology. [less ▲]

Detailed reference viewed: 71 (0 UL)
See detailDC and Pulsed Behaviour of Undoped and Doped AlGaN/GaN/SiC HEMTs before and after Si3N4 passivation
Bernát, J.; Marso, Michel UL; Fox, A. et al

in Proc. 5th Intern. Conf. Advanced Semicon. Dev. & Microsystems ASDAM’04 (2004)

Detailed reference viewed: 27 (0 UL)
Full Text
Peer Reviewed
See detailInfluence of layer structure on performance of AlGaN/GaN High Electron Mobility Transistors before and after passivation
Bernát, J.; Javorka, P.; Fox, A. et al

in Journal of Electronic Materials (2004), 33((2004)), 436-439

Detailed reference viewed: 66 (1 UL)
See detailGeneration of 1 THz radiation by photomixing in low-temperature-grown MBE GaAs
Mikulics, M.; Camara, I.; Marso, Michel UL et al

in Proc. 5th Intern. Conf. Advanced Semicon. Dev. & Microsystems ASDAM’04 (2004)

Detailed reference viewed: 57 (0 UL)
Full Text
Peer Reviewed
See detailInfluence of SiO/sub 2/ and Si/sub 3/N/sub 4/ passivation on AlGaN/GaN/Si HEMT performance,
Javorka, P.; Bernát, J.; Fox, A. et al

in Electronics Letters (2003), 39((2003)), 1155-1157

Different influence of SiO2 and Si3N4 passivation on performance of AlGaN=GaN=Si HEMTs is reported. DC characteristics are less enhanced by using SiO2 than Si3N4. This is in agreement with carrier ... [more ▼]

Different influence of SiO2 and Si3N4 passivation on performance of AlGaN=GaN=Si HEMTs is reported. DC characteristics are less enhanced by using SiO2 than Si3N4. This is in agreement with carrier concentration changes after passivation, as follows from Hall data. Small signal RF performance is degraded after applying SiO2 and enhanced after Si3N4 passivation, e.g. for unpassivated devices fTffi17 GHz which decreased to 9 GHz and increased to 28 GHz for SiO2 and Si3N4 respectively. The fmax=fT ratio has not changed after passivation. [less ▲]

Detailed reference viewed: 28 (0 UL)
Full Text
Peer Reviewed
See detailUltrafast and highly sensitive photodetectors fabricated on high-energy nitrogen-implanted GaAs,
Mikulics, M.; Marso, Michel UL; Kordoš, P. et al

in Applied Physics Letters (2003), 83

We have fabricated and tested metal–semiconductor–metal ~MSM! photodetectors based on nitrogen-ion-implanted GaAs. Nitrogen ions with energy of 700 and 880 keV, respectively, were implanted into epitaxial ... [more ▼]

We have fabricated and tested metal–semiconductor–metal ~MSM! photodetectors based on nitrogen-ion-implanted GaAs. Nitrogen ions with energy of 700 and 880 keV, respectively, were implanted into epitaxial GaAs films at an ion concentration of 331012 cm22. Ti/Au MSM photodetectors with 1-um-wide fingers were fabricated on top of the implanted GaAs. In comparison to low-temperature-grown GaAs photodetectors, produced in parallel in identical MSM geometry, the 880 keV N1-implanted photodetectors exhibited almost two orders of magnitude lower dark current ~10 nA at 1 V bias! and the responsivity more than doubled ~.20 mA/W at 20 V bias!. Illumination with 100-fs-wide, 810 nm wavelength laser pulses, generated ;2.5-ps-wide photoresponse signals with amplitudes as high as 2 V. The 2.5 ps relaxation time was the same for both the ion-implanted and low-temperature-grown devices and was limited by the MSM capacitance time constant. [less ▲]

Detailed reference viewed: 71 (0 UL)
Full Text
Peer Reviewed
See detailEffect of surface passivation on performance of AlGaN/GaN/Si HEMTs
Bernát, J.; Javorka, P.; Fox, A. et al

in Solid-State Electronics (2003), 47((2003)), 2097-2103

Performance of intentionally undoped and doped AlGaN/GaN/Si high electron mobility transistors (HEMTs) before and after passivation with SiO2 and Si3N4 is investigated. Hall effect measurements show ... [more ▼]

Performance of intentionally undoped and doped AlGaN/GaN/Si high electron mobility transistors (HEMTs) before and after passivation with SiO2 and Si3N4 is investigated. Hall effect measurements show higher impact of Si3N4 than SiO2 passivation on the carrier concentration increase in the channel. Improvements in DC performance of HEMTs after passivation with SiO2 and Si3N4 correspond to the changes in sheet carrier concentration. Small signal microwave characterisation shows a decrease (from 18.6 to 9 GHz) and an increase (from 18.4 to 28.8 GHz) of the current gain cut off frequency after SiO2 and Si3N4 passivation, respectively. Similar effect of passivation is found in microwave power changes––only about a half of the power is obtained after SiO2 passivation but more than doubled power results from Si3N4 passivation, measured at 2 GHz. Higher density of interface states for SiO2 than Si3N4 passivation is supposed to be responsible for these effects. However, for an optimal design of GaN-based power devices additional studies related to the interface between a passivation layer and GaN are needed. [less ▲]

Detailed reference viewed: 98 (0 UL)
Full Text
Peer Reviewed
See detailConductivity and Hall effect measurements on intentionally undoped and doped AlGaN/GaN heterostructures before and after passivation,
Bernat, J.; Javorka, P.; Marso, Michel UL et al

in Applied Physics Letters (2003), 83((2003)), 5455

Conductivity and Hall effect measurements were performed before and after Si3N4 passivation of intentionally undoped and doped AlGaN/GaN heterostructures on Si and SiC substrates. An increase of the sheet ... [more ▼]

Conductivity and Hall effect measurements were performed before and after Si3N4 passivation of intentionally undoped and doped AlGaN/GaN heterostructures on Si and SiC substrates. An increase of the sheet carrier density ~up to ;30%! and a slight decrease of the electron mobility ~less than 10%! are found in all samples after passivation. The passivation induced sheet carrier density is 1.5– 231012 cm22 in undoped samples and only 0.731012 cm22 in 5–1031018 cm23 doped samples. The decrease of the electron mobility after passivation is slightly lower in highly doped samples. The channel conductivity in both types of unpassivated samples on Si and SiC substrates increases with an increase in doping density. After passivation, a well-resolved increase of channel conductivity is observed in the undoped or lightly doped samples and nearly the same channel conductivity results in the highly doped samples. [less ▲]

Detailed reference viewed: 80 (0 UL)
Full Text
Peer Reviewed
See detailPhysics of imaging p-n junctions by scanning tunneling microscopy and spectroscopy
Jäger, N. D.; Marso, Michel UL; Salmeron, M. et al

in Physical Review. B : Condensed Matter (2003), ((2003)), 165307

Combined voltage-dependent scanning tunneling microscopy ~STM! images with atomic resolution, local scanning tunneling spectroscopy, and simulations of the potential distribution in the interface STM tip ... [more ▼]

Combined voltage-dependent scanning tunneling microscopy ~STM! images with atomic resolution, local scanning tunneling spectroscopy, and simulations of the potential distribution in the interface STM tip system are used to extract the physical imaging mechanisms of GaAs p-n interfaces in STM images. It is shown that ~i! the tip-induced changes of the potential near the interface result in the tunneling characteristics of the p-type (n-type! layer being dragged into the interfaces’ depletion region at positive ~negative! sample voltage. ~ii! This leads to a considerable reduction of the apparent width of the image of the depletion zone in STM images. ~iii! At small negative sample voltages, a pronounced depression line appears. The depression is directly correlated with the electronic interface. It arises from the interplay of competing current contributions from the valence and conduction bands. This understanding of the imaging process allows us to develop methods on how to extract accurate physical data about the properties of the electronic interfaces from scanning tunneling microscopy images. [less ▲]

Detailed reference viewed: 93 (0 UL)
Full Text
Peer Reviewed
See detailMaterial and Device Issues of AlGaN/GaN HEMTs on Silicon Substrates
Javorka, P.; Alam, A.; Marso, Michel UL et al

in Microelectronics Journal (2003), 34

Selected material and device issues related to the performance of AlGaN/GaN HEMTs on (111) Si substrates are reported. It is shown that these devices can sustain significantly higher dc power (16 W/mm ... [more ▼]

Selected material and device issues related to the performance of AlGaN/GaN HEMTs on (111) Si substrates are reported. It is shown that these devices can sustain significantly higher dc power (16 W/mm) than those grown on sapphire. Consequently smaller degradation in the device performance at higher temperatures (up to 400 8C) is demonstrated. Photoionisation spectroscopy reveals trap level of 1.85 eV, additional to two another levels found before in GaN-based HEMTs prepared on sapphire. Thus, AlGaN/GaN HEMTs on Si substrates demonstrate the viability of this technology for commercial application of high power rf devices. [less ▲]

Detailed reference viewed: 101 (2 UL)
Full Text
Peer Reviewed
See detailInfluence of doping concentration on DC and RF performance of AlGaN/GaN HEMTs on silicon substrate
Marso, Michel UL; Javorka, P.; Dikme, Y. et al

in Physica Status Solidi A. Applications and Materials Science (2003), (1), 179-182

AlGaN/GaN HEMTs with different carrier supply layers are fabricated on Si substrate, using MOVPE growth technique. The influence of the carrier supply doping concentration on the HEMT properties is ... [more ▼]

AlGaN/GaN HEMTs with different carrier supply layers are fabricated on Si substrate, using MOVPE growth technique. The influence of the carrier supply doping concentration on the HEMT properties is investigated by Hall measurements and by electrical DC and RF characterisation of transistor devices. Hall mobility is found to decrease with increasing sheet concentration, while the gate leakage current increases. The device with the highest carrier supply doping concentration of 1019 cm–3 is provided with a GaN cap layer to reduce gate leakage. The transistors based on modulation doped layer structures show much higher DC performance than the undoped device. Best RF properties are obtained for a doping level of 5 × 1018 cm–3. High frequency measurements exhibit fT and fMAX values of 35 GHz and 37 GHz, respectively, for devices with 300 nm gate length. [less ▲]

Detailed reference viewed: 100 (0 UL)
See detailPeculiarities of low frequency noise in GaN-based high electron mobility transistors
Vitusevich, S. A.; Petrychuk, M. V.; Klein, N. et al

in Proc. 17th Internat. Conf. Noise and Fluctuations ICNF (2003)

Detailed reference viewed: 24 (0 UL)
Full Text
Peer Reviewed
See detailWet low-temperature gate oxidation for nanoscale vertical field-effect transistors,
Goryll, M.; Moers, J.; Trellenkamp, S. et al

in Physica E (2003), 19(2003), 18-22

In this work, we present an approach towards improving a vertical eld-e ect transistor based on a narrow mesa that is capable of showing complete channel inversion. Contrary to similar concepts it does ... [more ▼]

In this work, we present an approach towards improving a vertical eld-e ect transistor based on a narrow mesa that is capable of showing complete channel inversion. Contrary to similar concepts it does not necessarily require the use of an SOI substrate due to the chosen vertical layer sequence. An important issue during process flow is the limited thermal budget in order to preserve the desired channel length. Here a low-temperature wet oxidation process is investigated to prevent dopant di ffusion in early process steps. Results on the thickness homogeneity and electrical properties of this gate oxide will be presented and discussed. [less ▲]

Detailed reference viewed: 65 (0 UL)
Full Text
Peer Reviewed
See detailInvestigation of traps in AlGaN/GaN HEMTs on silicon substrate
Wolter, M.; Marso, Michel UL; P.Javorka, J. et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2003), (7), 2360-2363

Deep levels in AlGaN/GaN heterostructures are known to be responsible for trapping processes like current collapse or dispersion. In order to investigate these processes we performed different ... [more ▼]

Deep levels in AlGaN/GaN heterostructures are known to be responsible for trapping processes like current collapse or dispersion. In order to investigate these processes we performed different measurements on HEMTs fabricated with heterostructures grown on silicon substrate. First by photoionization spectroscopy we found three different traps with activation energies of about 2.1 eV, 2.9 eV and 3.2 eV. Secondly, the temperature dependent relaxation of the drain current was investigated by the backgating current deep level transient spectroscopy (DLTS) method. Hereby we detected majority and minority carrier traps in the GaN buffer at the energies EV + 0.41 eV and EC – 0.55 eV, respectively. The latter energy can be attributed to the well known “E2” level in GaN. [less ▲]

Detailed reference viewed: 82 (1 UL)