References of "Javorka, P."
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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)

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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 ▲]

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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 ▲]

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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)

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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)

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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)

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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 ▲]

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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 ▲]

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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 ▲]

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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 ▲]

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See detailInvestigations on the influence of traps in AlGaN/GaN HEMTs
Wolter, M.; Javorka, P.; Marso, Michel UL et al

in EDMO (2001)

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See detailInvestigation of self-heating effects in AlGaN/GaN HEMTs
Kuzmík, J.; Javorka, P.; Alam, A. et al

in Proc. EDMO (2001)

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See detailVaractor Diodes based on an AlGaN/GaN HEMT layer structure
Marso, Michel UL; Wolter, M.; Bernát, J. et al

in EProc. EDMO (2001)

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See detailAlGaN/GaN HEMT Optimization Using the RoundHEMT Technology
Marso, Michel UL; Javorka, P.; Alam, A. et al

in Physica Status Solidi A. Applied Research (2001), 188

The electrical characterization of epitaxially grown HEMT layer systems for device fabrication is commonly performed by Hall measurements. However, the ultimate characterization of a HEMT layer system is ... [more ▼]

The electrical characterization of epitaxially grown HEMT layer systems for device fabrication is commonly performed by Hall measurements. However, the ultimate characterization of a HEMT layer system is the transistor device itself. The RoundHEMT concept meets the need for a device technology with few fabrication steps that allows a fast feedback to epitaxy while providing an evaluation of important electrical and also processing data. Even though nearly identical Hall data on structures with different thickness and doping concentration of the AlGaN layers suggest similar device properties, the RoundHEMTs resolve remarkable differences in device performance. The best layer structure was used to fabricate HEMTs with IDS = 700 mA/mm, fT = 35 GHz, and fmax = 70 GHz for LG = 0.2 mm. [less ▲]

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See detailAlGaN/GaN Round-HEMTs on (111) silicon substrates
Javorka, P.; Alam, A.; Nastase, N. et al

in Electronics Letters (2001), 37(2001), 1364-1366

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

AlGaN/GaN Round-HEMTs on silicon substrates have been realised and their static characteristics investigated. The AlGaN/GaN (x = 0.23) material structures were grown on (111) p-Si by LP-MOVPE. Devices with 0.3 mm gate length exhibit a saturation current of 0.82 A/mm, a good pinch-off and a peak extrinsic transconductance of 110 mS/mm. Highest saturation current reported so far and static output characteristics up to 20 V demonstrate that the devices are capable of handling 16 W/mm of static heat dissipation without any degradation of their performance. [less ▲]

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See detailAlGaN/GaN Varactor Diode for Integration in HEMT Circuits
Marso, Michel UL; Wolter, M.; Javorka, P. et al

in Electronics Letters (2001), 37(2001), 1476-1478

Fabrication and characterisation of metal-semiconductor-metal (MSM) diodes above an AlGaN/GaN HEMT layer system for varactor applications are reported. Device fabrication uses standard HEMT processing ... [more ▼]

Fabrication and characterisation of metal-semiconductor-metal (MSM) diodes above an AlGaN/GaN HEMT layer system for varactor applications are reported. Device fabrication uses standard HEMT processing steps, allowing integration in HEMT circuits without the need of sophisticated growth or etching techniques. Capacitancevoltage measurements exhibit CMAX/CMIN ratios up to 100, tunable by the electrode geometry. These results exceed best values for published heterostructure varactor diodes. Fabrication of AlGaN/GaN HEMTs on the same layer system with identical technology prove the potential for monolithic integration. [less ▲]

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See detailOptimization of AlGaN/GaN HEMT performance
Javorka, P.; Wolter, M.; Alam, A. et al

in Proc. EDMO (2001)

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See detailMaterial and Device Issues of GaN-based HEMTs
Kordoš, P.; Alam, A.; Betko, J. et al

in Proceedings of the 8th International Symposium on High Performance Electron Devices for Microwave and Optoelectronic Applications (EDMO), (2000)

Detailed reference viewed: 67 (0 UL)