References of "Marso, Michel 50002313"
     in
Bookmark and Share    
Full Text
See detailMaterial and Device Issues of AlGaN/GaN HEMTs on Silicon Substrates
Javorka, P.; Alam, A.; Marso, Michel UL et al

in Proceedings of the MRS Fall Meeting, Boston 2002 (2003)

Results on the preparation and properties of AlGaN/GaN HEMTs on silicon substrates are presented and selected issues related to the material structure and device performance devices are discussed ... [more ▼]

Results on the preparation and properties of AlGaN/GaN HEMTs on silicon substrates are presented and selected issues related to the material structure and device performance devices are discussed. Virtually crack-free AlGaN/GaN heterostructures (xAlN ≅ 0.25), with low surface roughness (rms of 0.64 nm), ns ≅ 1×1013 cm-2 and μ ≅ 1100 cm2/V s at 300 K, were grown by LP-MOVPE on 2-inch (111)Si substrates. HEMT devices with Lg = 0.3−0.7 μm were prepared by conventional device processing steps. Photoionization spectroscopy measurements have shown that a trap level of 1.85 eV, additional to two levels of 2.9 and 3.2 eV found before on GaN-based HEMTs on sapphire, is present in the structures investigated. Self-heating effects were studied by means of temperature dependent dc measurements. The channel temperature of a HEMT on Si increases with dissipated power much slower than for similar devices on sapphire substrate (e.g. reaches 95 and 320 °C on Si and sapphire, respectively, for 6 W/mm power). Prepared AlGaN/GaN/Si HEMTs exhibit saturation currents up to 0.91 A/mm, a good pinch-off, peak extrinsic transconductances up to 150 mS/mm and static heat dissipation capability up to ~16 W/mm. Unity current gain frequencies fT up to 21 and 32 GHz were obtained on devices with gate length of 0.7 and 0.5 μm, respectively. The saturation current and fT values are comparable to those known for similar devices using sapphire and SiC substrates. Properties of AlGaN/GaN/Si HEMTs investigated show that this technology brings a prospect for commercial application of high power rf devices. [less ▲]

Detailed reference viewed: 72 (0 UL)
Full Text
Peer Reviewed
See detailInvestigation of buffer traps in an AlGaN/GaN/Si high electron mobility transistor by backgating current deep level transient spectroscopy
Marso, Michel UL; Wolter, M.; Javorka, P. et al

in Applied Physics Letters (2003), 82

The influence of a substrate voltage on the dc characteristics of an AlGaN/GaN high electron mobility transistor ~HEMT! on silicon ~111! substrate is profited to investigate traps that are located between ... [more ▼]

The influence of a substrate voltage on the dc characteristics of an AlGaN/GaN high electron mobility transistor ~HEMT! on silicon ~111! substrate is profited to investigate traps that are located between the substrate and the two-dimensional electron gas channel. The transient of the drain current after applying a negative substrate voltage is evaluated in the temperature range from 30 to 100 °C. With this method, known as backgating current deep level transient spectroscopy, majority carrier traps with activation energy of 200 meV as well as minority carrier traps at 370 meV are identified. The experiments are performed on completed HEMTs, allowing the investigation of the influence of device fabrication technology. [less ▲]

Detailed reference viewed: 73 (0 UL)
Full Text
See detailBackgating high-current and breakdown characterisation of AlGaN/GaN HEMTs on silicon substrates
Kuzmik, J.; Blaho, M.; Pogany, D. et al

in Proceedings of the ESSDERC 2003. Estoril, Portugal (2003)

Backgating effect as well as breakdown and high-current performance of AlGaN/GaN HEMTs on silicon substrates are studied. The material structure of investigated devices differ in the thickness of ... [more ▼]

Backgating effect as well as breakdown and high-current performance of AlGaN/GaN HEMTs on silicon substrates are studied. The material structure of investigated devices differ in the thickness of stressrelaxing intermediate layer sequence (~1 μm and ~2.5 μm thick). It is shown that the transistor backgating effect is reduced for the thicker sequence. Similarly, the reverse gate current is two orders of the magnitude lower and the gate-drain breakdown voltage increases substantially in devices with the thicker sequence. Increase from ~40 V to ~160 V of the HEMT blocking capability measured under electrostatic discharge-like conditions is also observed. [less ▲]

Detailed reference viewed: 93 (0 UL)
Full Text
Peer Reviewed
See detailPhotoionization spectroscopy of traps in doped and undoped AlGaN/GaN HEMTs
Wolter, M.; Javorka, P.; Marso, Michel UL et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2002), (1), 82-85

Deep-level defects and surface states are supposed to be responsible for the limitation of AlGaN/GaN high electron mobility transistor (HEMT) performance. In order to investigate the influence of these ... [more ▼]

Deep-level defects and surface states are supposed to be responsible for the limitation of AlGaN/GaN high electron mobility transistor (HEMT) performance. In order to investigate the influence of these traps, photoionization spectroscopy was used to study doped and undoped HEMTs grown on sapphire in different metalorganic vapour-phase epitaxy reactors. This measurement technique is based on the optical reversion of the current collapse and it allows one to determine photoionization cross-sections of the participating traps. For doped and undoped HEMTs nearly the same two defect levels with excitation energies of 3.2 eV and 2.9 eV were determined. By varying the source–gate voltage it was found that the photoionization cross-section is reduced for positive gate bias, i.e. the virtual gate on the gate–drain access region is partially neutralized due to the removal of trapped electrons from surface states. [less ▲]

Detailed reference viewed: 76 (0 UL)
Full Text
Peer Reviewed
See detailFabrication and performance of AlGaN/GaN HEMTs on (111) Si substrates
Javorka, P.; Alam, A.; Marso, Michel UL et al

in Physica Status Solidi A. Applications and Materials Science (2002), 194(2), 472-475

In the current work the performance of AlGaN/GaN HEMTs fabricated on silicon substrates is presented. The AlGaN/GaN material structures were grown on (111) Si by MOVPE. Static I–V characteristics with a ... [more ▼]

In the current work the performance of AlGaN/GaN HEMTs fabricated on silicon substrates is presented. The AlGaN/GaN material structures were grown on (111) Si by MOVPE. Static I–V characteristics with a saturation current of 0.91 A/mm and a peak extrinsic transconductance of 122 mS/mm were measured and show minimal thermal effects. For devices with a gate length of 0.7 um and 0.5 um, a unity gain frequency of 20 GHz and 32 GHz and a maximum frequency of oscillation of 22 GHz and 27 GHz, respectively were obtained. The unity gain frequencies are the highest values reported so far on AlGaN/GaN/Si HEMTs and fully comparable to those known for devices using sapphire and SiC substrates. However, the fmax to fT ratio is only about 1, which indicates on parasitic conduction through the Si substrate under small signal conditions. It is shown that the saturation current and the transconductance decrease much less with increased temperature than known for similar devices grown on sapphire. [less ▲]

Detailed reference viewed: 69 (0 UL)
See detailMSM Diodes Based on an AlGaN/GaN HEMT Layer Structure for Varactor and Photodiode Application
Marso, Michel UL; Bernát, J.; Wolter, M. et al

in , Proc. 4th Intern. Conf. Advanced Semicon. Dev. & Microsystems (2002)

Detailed reference viewed: 66 (0 UL)
Full Text
Peer Reviewed
See detailDetermination of channel temperature in AlGaN/GaN HEMTs grown on sapphire and silicon substrates using DC characterization method
Kuzmík, J.; Javorka, P.; Alam, A. et al

in IEEE Transactions on Electron Devices (2002), 49(8), 1496-1498

Self-heating effects and temperature rise in AlGaN/GaN HEMTs grown on silicon and sapphire substrates are studied, exploiting transistor dc characterization methods. A negative differential output ... [more ▼]

Self-heating effects and temperature rise in AlGaN/GaN HEMTs grown on silicon and sapphire substrates are studied, exploiting transistor dc characterization methods. A negative differential output resistance is observed for high dissipated power levels. An analytical formula for a source-drain current drop as a function of parasitic source resistance and threshold voltage changes is proposed to explain this behavior. The transistor source resistance and threshold voltage is determined experimentally at different elevated temperatures to construct channel temperature versus dissipated power transfer characteristic. It is found that the HEMT channel temperature increases rapidly with dissipated power and at 6 W/mm reaches values of 320 C for sapphire and 95 C for silicon substrate, respectively. [less ▲]

Detailed reference viewed: 64 (0 UL)
Full Text
See detailMaterial and Device Issues of AlGaN/GaN HEMTs on Silicon Substrates
Javorka, P.; Alam, A.; Marso, Michel UL et al

in Mat. Res. Soc. Symp. Proc. Vol. 743 (2002), 743, L9.1.1

Results on the preparation and properties of AlGaN/GaN HEMTs on silicon substrates are presented and selected issues related to the material structure and device performance devices are discussed ... [more ▼]

Results on the preparation and properties of AlGaN/GaN HEMTs on silicon substrates are presented and selected issues related to the material structure and device performance devices are discussed. Virtually crack-free AlGaN/GaN heterostructures (xAlN ≅ 0.25), with low surface roughness (rms of 0.64 nm), ns ≅ 1×1013 cm-2 and μ ≅ 1100 cm2/V s at 300 K, were grown by LP-MOVPE on 2-inch (111)Si substrates. HEMT devices with Lg = 0.3−0.7 μm were prepared by conventional device processing steps. Photoionization spectroscopy measurements have shown that a trap level of 1.85 eV, additional to two levels of 2.9 and 3.2 eV found before on GaN-based HEMTs on sapphire, is present in the structures investigated. Self-heating effects were studied by means of temperature dependent dc measurements. The channel temperature of a HEMT on Si increases with dissipated power much slower than for similar devices on sapphire substrate (e.g. reaches 95 and 320 °C on Si and sapphire, respectively, for 6 W/mm power). Prepared AlGaN/GaN/Si HEMTs exhibit saturation currents up to 0.91 A/mm, a good pinch-off, peak extrinsic transconductances up to 150 mS/mm and static heat dissipation capability up to ~16 W/mm. Unity current gain frequencies fT up to 21 and 32 GHz were obtained on devices with gate length of 0.7 and 0.5 μm, respectively. The saturation current and fT values are comparable to those known for similar devices using sapphire and SiC substrates. Properties of AlGaN/GaN/Si HEMTs investigated show that this technology brings a prospect for commercial application of high power rf devices. [less ▲]

Detailed reference viewed: 62 (0 UL)
See detailHigh-performance AlGaN/GaN HEMTs on silicon substrates
Javorka, P.; Alam, A.; Fox, A. et al

in Proc. 4th Intern. Conf. Advanced Semicon. Dev. & Microsystems (2002)

Detailed reference viewed: 53 (0 UL)
See detailFreestanding LT GaAs as a subpicosecond photoconductive switch and high-voltage photomixer
Mikulics, M.; Siebel, F.; Zheng, X. et al

in Abstract book of 4th Symposium on Non-Stoichiometric III-V Compounds (2002), Physik Mikrostrukturierter Halbleiter 27

Detailed reference viewed: 20 (1 UL)
Full Text
Peer Reviewed
See detailInfluence of Surface Treatments on DC-Performance of GaN-Based HFETs
Mistele, D.; Rotter, T.; Bougrioua, Z. et al

in Physica Status Solidi A. Applications and Materials Science (2002), 194(2), 452-455

This work reports on the influence of the surface and the gate length on the performance of AlGaN/GaN based Hetero Field Effect Transistors (HFETs). Differently NH4Sx treated surfaces result in variation ... [more ▼]

This work reports on the influence of the surface and the gate length on the performance of AlGaN/GaN based Hetero Field Effect Transistors (HFETs). Differently NH4Sx treated surfaces result in variation of the drain current IDmax of more then 100%. Gate recessing by photoelectrochemical treatment changes the threshold voltage Vth but affects the drain current little. Next, the reduction of the gate length increases the IDmax further by more than 60%. The IDmax values for the transistors are 350 mA mm––1 for the NH4Sx-treated, 850 mA for the untreated, and 1.43 A mm––1 for the one with a 0.2 mm gate length. The corresponding transconductances gm are 66, 150, and 280 mS mm––1, respectively. Surface analysis with Auger Electron Spectroscopy (AES) and contact characterization (TLM) reveals, that the NH4Sx treatment removes the native oxide and increases the contact resistance as well. Therefore we attribute the increase of IDmax and gm mainly to a beneficial behavior of gallium-oxide at the surface on the sheet carrier density nS of the 2DEG at the heterointerface. [less ▲]

Detailed reference viewed: 36 (1 UL)
See detailInvestigation of current collapse in doped and undoped AlGaN/GaN HEMTs
Wolter, M.; Javorka, P.; Marso, Michel UL et al

in Proc. 4th Intern. Conf. Advanced Semicon. Dev. & Microsystems (2002)

Detailed reference viewed: 85 (0 UL)
See detailThin low-temperature gate oxides for vertical field-effect transistor, ,
Goryll, M.; Moers, J.; Trellenkamp, St et al

in Proc. 4th Intern. Conf. Advanced Semicon. Dev. & Microsystems (2002)

Detailed reference viewed: 22 (0 UL)
See detailRF small-signal and power characterization of AlGaN/GaN HEMTs
Fox, A.; Marso, Michel UL; Javorka, P. et al

in , Proc. 4th Intern. Conf. Advanced Semicon. Dev. & Microsystems (2002)

Detailed reference viewed: 65 (0 UL)
See detailGeneration of 460 GHz radiation by photomixing in low-temperature-grown MBE GaAs
Mikulics, M.; Siebel, F.; Fox, A. et al

in Proc. 4th Intern. Conf. Advanced Semicon. Dev. & Microsystems (2002)

Detailed reference viewed: 61 (0 UL)
Full Text
Peer Reviewed
See detailInvestigation of AlGaN/GaN HEMTs on Si substrate using backgating
Marso, Michel UL; Wolter, M.; Javorka, P. et al

in Physica Status Solidi C. Current Topics in Solid State Physics (2002), (1), 65-68

The influence of a substrate voltage on the dc characteristics of an AlGaN/GaN HEMT on silicon (111) substrate is investigated. This effect, known as backgating, is used to study traps that are located ... [more ▼]

The influence of a substrate voltage on the dc characteristics of an AlGaN/GaN HEMT on silicon (111) substrate is investigated. This effect, known as backgating, is used to study traps that are located between substrate and 2DEG channel. The transient of the drain current after applying a negative substrate voltage is evaluated for measurements with and without illumination. Several trap contributions are resolved by measurements at different photon energies. A photocurrent is observed up to 600 nm wavelength. Up to this wavelength the backgating effect can be compensated and the drain current restored by a short light pulse. The experiments are performed on completed HEMTs, allowing investigation of the influence of device fabrication technology. [less ▲]

Detailed reference viewed: 68 (3 UL)
Full Text
Peer Reviewed
See detailGrowth and characterisation of AlGaN/GaN-HEMTs on silicon substrates,
Kalisch, H.; Dikme, Y.; Gerstenbrandt, G. et al

in Physica Status Solidi A. Applications and Materials Science (2002), 194(2), 464-467

In order to analyse and to compare the properties of AlGaN/GaN HEMT on silicon and on sapphire substrates, studies on both layers and device types have been performed. Besides the substantially lower ... [more ▼]

In order to analyse and to compare the properties of AlGaN/GaN HEMT on silicon and on sapphire substrates, studies on both layers and device types have been performed. Besides the substantially lower substrate costs compared to SiC, the use of silicon as substrate provides the advantage of a higher thermal conductivity compared to sapphire allowing a more efficient heat removal from the device and thus higher RF power densities. On silicon, up to 900 nm of GaN as well as HEMT structures have been deposited and characterised regarding their structural, optical and electrical properties. HEMT devices with various gate lengths were processed and measured onwafer under continuous and pulsed operation conditions. The properties of the layers and devices on silicon substrates are developing to become comparable to those based on sapphire and silicon carbide. [less ▲]

Detailed reference viewed: 38 (0 UL)
Full Text
Peer Reviewed
See detailAlGaN/GaN HEMTs on Silicon Substrates with f¬T of 32/20 GHz and fmax of 27/22 GHz for 0.5/0.7 µm gate length,
Javorka, P.; Alam, A.; Fox, A. et al

in Electronics Letters (2002), 38(2002), 288-289

AlGaN/GaN HEMTs on silicon substrates have been realised and their static and small signal characteristics investigated. The AlGaN/GaN (x=0.23) material structures were grown on (111) p-Si by LP-MOVPE ... [more ▼]

AlGaN/GaN HEMTs on silicon substrates have been realised and their static and small signal characteristics investigated. The AlGaN/GaN (x=0.23) material structures were grown on (111) p-Si by LP-MOVPE. Devices exhibit a saturation current density of 0.53 to 0.68 A/mm and a peak extrinsic transconductance of 110 mS/mm. A unity gain frequency of 20 and 32 GHz and a maximum frequency of oscillation of 22 and 27 GHz are obtained for devices with a gate length of 0.7 and 0.5 mm, respectively. These values are the highest reported so far on AlGaN=GaN=Si HEMTs and are comparable to those known for devices using sapphire and SiC substrates. [less ▲]

Detailed reference viewed: 21 (0 UL)
Full Text
Peer Reviewed
See detailAnnealing of Schottky contacts deposited on dry etched AlGaN/GaN,
Kuzmík, J.; Javorka, P.; Marso, Michel UL et al

in Semiconductor Science & Technology (2002), 17((2002).), 76-78

The influence of annealing on properties of Pt Schottky contacts deposited on the electron cyclotron resonance plasma etched surface of an AlGaN/GaN heterostructure has been investigated. It is found that ... [more ▼]

The influence of annealing on properties of Pt Schottky contacts deposited on the electron cyclotron resonance plasma etched surface of an AlGaN/GaN heterostructure has been investigated. It is found that rapid thermal annealing (450 ◦C and 40 s in nitrogen gas), performed after metal deposition, allows for the preparation of Schottky contacts with similar or better properties than those obtained on a non-etched surface. This procedure is suitable for the realization of recessed high-quality Schottky contacts of AlGaN/GaN HEMTs. [less ▲]

Detailed reference viewed: 79 (0 UL)
Full Text
Peer Reviewed
See detailAlGaN/GaN HEMTs on (111) Silicon Substrates
Javorka, P.; Alam, A.; Wolter, M. et al

in IEEE Electron Device Letters (2002), 23(2002), 4-6

AlGaN/GaN HEMTs on silicon substrates have been fabricated and their static and small-signal RF characteristics investigated. The AlGaN/GaN material structures were grown on (111) p-Si by LP-MOVPE ... [more ▼]

AlGaN/GaN HEMTs on silicon substrates have been fabricated and their static and small-signal RF characteristics investigated. The AlGaN/GaN material structures were grown on (111) p-Si by LP-MOVPE. Devices exhibit a saturation current of 0.91 A/mm, a good pinchoff and a peak extrinsic transconductance of 122 mS/mm. A unity current gain frequency of 12.5 GHz and fmax/fT=0.83 were obtained. The highest saturation current reported so far, static output characteristics of up to 20 V and breakdown voltage at pinchoff higher than 40 V demonstrate that the devices are capable of handling 16 W/mm static heat dissipation. [less ▲]

Detailed reference viewed: 66 (2 UL)