References of "Marso, Michel 50002313"
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See detailTechnology related issues regarding fabrication of AlGaN/GaN-based MOSHFETs with GdScO3 as dielectric,
Heidelberger, G.; Roeckerath, M.; Steins, R. et al

in Proc. 6th Intern. Conf. Advanced Semicon. Dev. & Microsystems ASDAM’06 (2006)

Starting out from our well established process for AlGaN/GaN HFETs we discuss ways to enrich the process in order to fabricate Metal-Oxide-Semiconductor HFETs (MOSHFETs) with a Gadolinium Scandate (GdScO3 ... [more ▼]

Starting out from our well established process for AlGaN/GaN HFETs we discuss ways to enrich the process in order to fabricate Metal-Oxide-Semiconductor HFETs (MOSHFETs) with a Gadolinium Scandate (GdScO3) insulation layer. In particular, adequate processing orders, various etching procedures and possible drawbacks of the GdScO3 deposition process on ohmic contacts are discussed. Making use of the gained knowledge we fabricated GdScO3-MOSHFETs for the first time. Compared to a conventional HFET the new device shows a higher saturation drain current and a lower gate leakage current. Nevertheless, the potential insulating properties of GdScO3 are not fully exploited yet and further optimization of the deposition process is needed. [less ▲]

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See detailRF characterization and modeling of AlGaN/GaN based HFETs and MOSHFETs
Fox, A.; Marso, Michel UL; Heidelberger, G. et al

in Proc. 6th Intern. Conf. Advanced Semicon. Dev. & Microsystems ASDAM’06 (2006) (2006)

An increased RF-Performance of heterojunction field-effect transistor was found to be due to passivation and in addition a SiO2 insulation underneath the gate metallization. This leads to an increase of ... [more ▼]

An increased RF-Performance of heterojunction field-effect transistor was found to be due to passivation and in addition a SiO2 insulation underneath the gate metallization. This leads to an increase of cutoff frequency from 17 GHz up to 24 GHz for devices with 500 nm gate length. The RF output power increased from 4.1 to 6.7 W/mm at 7 GHz. RF simulation based on measured S-parameter showed a decrease of gate-source-capacitance and transconductance for devices with a dielectric layer underneath the gate metallization. The increase of the ratio gm/Cgs of about 25% is in agreement with the measured cutoff frequency ft. [less ▲]

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See detailUltrafast Phenomena in Freestanding LT-GaAs Devices
Marso, Michel UL; Mikulics, M.; Adam, R. et al

in Acta Physica Polonica A (2005), VOL 107; PART 1

We report on the fabrication and high-frequency performance of our photodetectors and photomixers based on freestanding low-temperature-grown GaAs. The MBE-grown low-temperature GaAs layers are lifted ... [more ▼]

We report on the fabrication and high-frequency performance of our photodetectors and photomixers based on freestanding low-temperature-grown GaAs. The MBE-grown low-temperature GaAs layers are lifted from the native GaAs substrate and transferred on top of variety of host substrates. The freestanding devices exhibit breakdown electrical ¯elds above 200 kV/cm and dark currents below 3 £ 10¡7 A at 100 V bias. Device photoresponse shows 0.55 ps wide electrical transients with voltage amplitudes up to 1.3 V, measured using an electro-optical sampling technique with 100 fs wide laser pulses. Photomixing experiments at 460 GHz yield a 9 times higher output power for the freestanding device on Si/SiO2 host substrate compared to the native substrate. [less ▲]

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See detailInfluence of passivation-induced stress on the performance of AlGaN/GaN HEMTs
Gregusova, Dagmar; Bernát, J.; Drzik, M. et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2005), 2(7), 2619-2622

This paper reports on properties of intentionally undoped AlGaN/GaN/sapphire-based high electron mobility transistors (HEMTs) before and after passivation with SiO2 and Si3N4. Our results indicate that ... [more ▼]

This paper reports on properties of intentionally undoped AlGaN/GaN/sapphire-based high electron mobility transistors (HEMTs) before and after passivation with SiO2 and Si3N4. Our results indicate that the DC performance of the AlGaN/GaN HEMTs improved significantly as the stress in the passivation layer increased from compressive to tensile. It corresponded to changes in the sheet carrier concentration. Unlike the DC properties, RF properties of the HEMTs were less sensitive to the stress. [less ▲]

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See detailInfluence of carrier supply doping on the RF properties of AlGaN/GaN/SiC high-electron-mobility transistors
Marso, Michel UL; Bernát, J.; Javorka, P. et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2005), 2(7), 2611-2614

We have fabricated undoped as well as modulation-doped AlGaN/GaN HEMTs on SiC substrate. The influence of the carrier supply layer on device performance is investigated by Hall, channel conductivity ... [more ▼]

We have fabricated undoped as well as modulation-doped AlGaN/GaN HEMTs on SiC substrate. The influence of the carrier supply layer on device performance is investigated by Hall, channel conductivity, small signal RF and delay time evaluation. While the doping layer improves the DC performance it degrades the RF behaviour of the device with the highest carrier supply doping of 5x1018 cm–3. The channel conductivity measurements show identical dependence of the mobility on carrier concentration for all samples. The saturation velocity, extracted by evaluation of the total delay time as function of the inverse drain current, decreases from 0.86x107 cm/s for the undoped device to 0.7x107 cm/s for the highest doped HEMT. This result shows that the degradation of RF performance is due to the reduction of the effective saturation velocity caused by the carrier supply layer. [less ▲]

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See detailPhotomixers fabricated on nitrogen-ion-implanted GaAs
Mikulics, M.; Marso, Michel UL; Cámara Mayorga, I. et al

in Applied Physics Letters (2005), 87(4), 41106-1-3

We report on fabrication and measurement of photomixers based on nitrogen-ion-implanted GaAs. We used energies of 500 keV, 700 keV, and 880 keV to implant N+ ions into GaAs substrates with an ion ... [more ▼]

We report on fabrication and measurement of photomixers based on nitrogen-ion-implanted GaAs. We used energies of 500 keV, 700 keV, and 880 keV to implant N+ ions into GaAs substrates with an ion concentration of 3 1012 cm−2. The resulting material exhibited 110 fs carrier lifetime due to implantation-induced defects. Our photomixers were fabricated as metal-semiconductor-metal devices, placed at the feed point of a broadband antenna. Optoelectronic measurements were performed in the wavelength range between 350 nm and 950 nm. In comparison to their counterparts photomixers fabricated on low-temperature-grown GaAs the N+-implanted GaAs photomixers exhibit improvements on both the output power and responsivity. A maximal responsivity of above 100 mA/W was achieved and we did not observe any dependence of the mixer cut-off frequency on the bias voltage. These characteristics make N+-implanted GaAs the material of choice for efficient optoelectronic photomixers. [less ▲]

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See detailSize-dependent Photoconductivity in MBE-Grown GaN-Nanowires
Calarco, Raffaella; Marso, Michel UL; Richter, Thomas et al

in Nano Letters (2005), 5(5), 981-984

We report on electrical transport in the dark and under ultraviolet (UV) illumination through GaN nanowhiskers grown by molecular beam epitaxy (MBE), which is sensitively dependent on the column diameter ... [more ▼]

We report on electrical transport in the dark and under ultraviolet (UV) illumination through GaN nanowhiskers grown by molecular beam epitaxy (MBE), which is sensitively dependent on the column diameter. This new effect is quantitatively described by a size dependent surface recombination mechanism. The essential ingredient for the interpretation of this effect is a diameter dependent recombination barrier, which arises from the interplay between column diameter and space charge layer extension at the column surface. [less ▲]

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See detailUltrafast metal-semiconductor-metal photodetectors on low-temperature-grown GaN
Mikulics, M.; Marso, Michel UL; Javorka, P. et al

in Applied Physics Letters (2005), 86(21), 211110

We have fabricated and characterized ultrafast metal-semiconductor-metal photodetectors based on low-temperature-grown sLTd GaN. The photodetector devices exhibit up to 200 kV/cm electric breakdown fields ... [more ▼]

We have fabricated and characterized ultrafast metal-semiconductor-metal photodetectors based on low-temperature-grown sLTd GaN. The photodetector devices exhibit up to 200 kV/cm electric breakdown fields and subpicosecond carrier lifetime. We recorded as short as 1.4-ps-wide electrical transients using 360-nm-wavelength and 100-fs-duration laser pulses, that is corresponding to the carrier lifetime of 720 fs in our LT GaN material. [less ▲]

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See detailSiO2 /AlGaN/GaN MOSHFET with 0.7 µm gate-length and fmax / fT of 40/24 GHz
Bernát, J.; Gregusová, D.; Heidelberger, G. et al

in Electronics Letters (2005), 41(11), 667-668

The performance of SiO2/AlGaN/GaN MOSHFETs is described. The C–V measurements showed slight increase in sheet carrier density after applying 12 nm-thick PECVD SiO2. The devices exhibited gate leakage ... [more ▼]

The performance of SiO2/AlGaN/GaN MOSHFETs is described. The C–V measurements showed slight increase in sheet carrier density after applying 12 nm-thick PECVD SiO2. The devices exhibited gate leakage current of 5 .10 ^-10 A/mm. Small-signal RF characterisation of 0.7 mm gate length devices yielded an fT of 24 GHz and an fmax of 40 GHz, which are comparable to those typical for state-of-the-art AlGaN/GaN HFETs. [less ▲]

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See detailGrowth and properties of GaN and AlN layers on silver substrates
Mikulics, Martin; Kočan, Martin; Rizzi, Angela et al

in Applied Physics Letters (2005), 87

We report on the preparation and properties of GaN and AlN layers grown by molecular-beam epitaxy on silver metal substrates. X-ray diffraction rocking curves show polycrystalline character of GaN with ... [more ▼]

We report on the preparation and properties of GaN and AlN layers grown by molecular-beam epitaxy on silver metal substrates. X-ray diffraction rocking curves show polycrystalline character of GaN with high preferential GaN 11-22 orientation. An intermetallic phase of Ga3Ag is found at the GaN/Ag interface. On the other hand, AlN layers exhibit a monocrystalline structure with a growth direction of 0002 . Schottky diodes prepared on GaN layers show good rectifying behavior and relatively low leakage current 10−3 A/cm2 . These results indicate that the III-nitride growth on metallic substrates might be used for low-cost and large-area electronic and photonic devices. [less ▲]

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See detailLow Current Dispersion and Low Bias-stress Degradation of Unpassivated GaN/AlGaN/GaN/SiC HEMTs
Bernát, J.; Pierobon, R.; Marso, Michel UL et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2005), 2(7), 2676-2679

The performance of unpassivated GaN/AlGaN/GaN/SiC HEMTs with intentionally undoped and doped barrier structures are extensively studied. No drain current dispersion between DC and 50 ns pulses on doped ... [more ▼]

The performance of unpassivated GaN/AlGaN/GaN/SiC HEMTs with intentionally undoped and doped barrier structures are extensively studied. No drain current dispersion between DC and 50 ns pulses on doped devices and less than 10% dispersion on undoped ones is observed. The full (100%) current recovery on undoped sample was measured in 1μs. The drain current extrapolated from 2 GHz large signal measurements corresponds to the measured static drain current confirming negligible current dispersion of our devices. Insignificant (<5 %) degradation in overall device performance parameters (IDs, gm, fT, fmax, Pout) on both undoped and doped structures after 12-hour-long bias stress was obtained. These results documents that suitable device performances can be obtained also on unpassivated GaN-based HEMTs. [less ▲]

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See detailHigh-power SiO2/AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors
Kordoš, P.; Heidelberger, G.; Bernát, J. et al

in Applied Physics Letters (2005), 87(14), 143501-143504

We report on SiO2 /AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors MOSHFETs , which exhibit a 6.7 W/mm power density at 7 GHz. Unpassivated and SiO2-passivated heterostructure ... [more ▼]

We report on SiO2 /AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors MOSHFETs , which exhibit a 6.7 W/mm power density at 7 GHz. Unpassivated and SiO2-passivated heterostructure field-effect transistors HFETs were also investigated for comparison. Deposited 12 nm thick SiO2 yielded an increase of the sheet carrier density from 7.6 .10^12 to 9.2 .10^12 cm−2 and a subsequent increase of the static drain saturation current from 0.75 to 1.09 A/mm. The small-signal rf characterization of the MOSHFETs showed an extrinsic current gain cutoff frequency fT of 24 GHz and a maximum frequency of oscillation fmax of 40 GHz. The output power of 6.7 W/mm of the MOSHFETs measured at 7 GHz is about two times larger than that of HFETs. The results obtained demonstrate the suitability of GaN-based MOSHFETs for high-power electronics. [less ▲]

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See detailWedge-shaped layers from porous silicon: the basics of laterally graded interference filters
Bohn, H. G.; Marso, Michel UL

in Physica Status Solidi A. Applied Research (2005), 202(8), 1437-1442

The process of making laterally graded interference filters has been reanalyzed. A simple and consistent picture arises if one applies a constant electric field perpendicular to the etch current instead ... [more ▼]

The process of making laterally graded interference filters has been reanalyzed. A simple and consistent picture arises if one applies a constant electric field perpendicular to the etch current instead of a constant current. The system is quantitatively modeled by means of a pure ohmic equivalent circuit model. [less ▲]

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See detailLarge-area traveling-wave photonic mixers for increased continuous terahertz power
Michael, E. A.; Vowinkel, B.; Schieder, R. et al

in Applied Physics Letters (2005), 86(11), 111120-111123

A large-aperture design for terahertz traveling-wave photomixers, continuously pumped free space by two detuned diode lasers, is proposed and experimentally verified for devices based on low-temperature ... [more ▼]

A large-aperture design for terahertz traveling-wave photomixers, continuously pumped free space by two detuned diode lasers, is proposed and experimentally verified for devices based on low-temperature-grown GaAs sLT-GaAsd. It combines the advantages of conventional interdigitated small-area structures and traveling-wave devices. An output power of 1 µW at the mixing frequency of 1 THz was measured in initial testing, which meets local oscillator power requirements for superconducting heterodyne mixer devices. [less ▲]

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See detailUltrafast Low-Temperature-Grown Epitaxial GaAs Photodetectors Transferred on Flexible Plastic Substrates
Mikulics, M.; Adam, R.; Marso, Michel UL et al

in IEEE Photonics Technology Letters (2005), 17(8), 1725-1727

We demonstrate low-temperature (LT)-grown GaAs photodetectors transferred on flexible polyethylene terephthalate (PET) plastic substrates. The LT-GaAs layer was patterned into 20 20 m2 chips, which after ... [more ▼]

We demonstrate low-temperature (LT)-grown GaAs photodetectors transferred on flexible polyethylene terephthalate (PET) plastic substrates. The LT-GaAs layer was patterned into 20 20 m2 chips, which after placing on the PET substrates were integrated with coplanar strip transmission lines. The devices exhibit low dark currents ( 2 10 8 A), subpicosecond photoresponse time, and signal amplitudes up to 0.9 V at the bias voltage of 80 V and under laser beam excitation power of 8 mW at 810-nm wavelength. At the highest bias ( 80 V) level, an increase of the response time (up to 1.3 ps) was observed and attributed to the influence of heating effects due to low thermal conductivity of PET. Our LT-GaAs-on-PET photodetectors withstand hundredfold mechanical bending of the substrate and are intended for applications in hybrid optoelectronic circuits fabricated on noncrystalline substrates, in terahertz imaging, and in biology-related current-excitation tests. [less ▲]

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See detailNitrogen implanted GaAs for ultrafast photodetectors and photomixers
Mikulics, M.; Wolter, M. J.; Marso, Michel UL et al

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

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See detailInfluence of a carrier supply layer on carrier density and drift mobility of AlGaN/GaN/SiC high-electron-mobility transistors
Marso, Michel UL; Bernát, J.; Javorka, P. et al

in Applied Physics Letters (2004), 84 (2004)

Sheet carrier concentration and low-field drift mobility of intentionally undoped and modulation-doped AlGaN/GaN heterostructures on SiC substrate were evaluated by capacitance-voltage and channel ... [more ▼]

Sheet carrier concentration and low-field drift mobility of intentionally undoped and modulation-doped AlGaN/GaN heterostructures on SiC substrate were evaluated by capacitance-voltage and channel conductivity measurements. Sheet carrier concentration and average mobility at 0 V gate bias correspond to standard Hall results. Sheet carrier density increases from 6.831012 cm22 for the undoped sample up to 131013 cm22 for the device with the highest doping concentration, while the mobility decreases from 1800 to 1620 cm2/V s. The local mobility, on the other hand, depends only on the actual sheet carrier density and is not influenced by the doping concentration of the carrier supply layer. It reaches a maximum value of 2100 cm2/Vs at a carrier density of 331012 cm22. [less ▲]

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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

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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)

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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)

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