@inproceedings{SchottKuhnertLenketal., author = {Schott, Matthias and Kuhnert, Holger and Lenk, Friedrich and Hilsenbeck, Jochen and W{\"u}rfl, Joachim and Heinrich, Wolfgang}, title = {38 GHz push-push GaAs-HBT MMIC oscillator}, series = {2002 IEEE MTT-S International Microwave Symposium digest, June 2 - 7, 2002, Washington State Convention \& Trade Center, Seattle, Washington, vol. 2}, booktitle = {2002 IEEE MTT-S International Microwave Symposium digest, June 2 - 7, 2002, Washington State Convention \& Trade Center, Seattle, Washington, vol. 2}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-7239-5}, doi = {10.1109/MWSYM.2002.1011761}, pages = {839 -- 842}, abstract = {Two differential coplanar MMIC HBT oscillators are presented, a fixed frequency and a VCO version. They provide single-ended output at the second harmonic at 38 GHz as well as differential output at 19 GHz. The oscillators show excellent phase noise performance, the fixed-frequency type reaches -95 dBc/Hz at the fundamental frequency and -89 dBc/Hz at the second harmonic, at 100 kHz offset.}, language = {en} } @inproceedings{LenkSchottHilsenbecketal., author = {Lenk, Friedrich and Schott, Matthias and Hilsenbeck, Jochen and W{\"u}rfl, Joachim and Heinrich, Wolfgang}, title = {Low phase-noise monolithic GaInP/GaAs-HBT VCO for 77 GHz}, series = {2003 IEEE MTT-S International Microwave Symposium digest, June 8 - 13, 2003, Pennsylvania Convention Center, Philadelphia, Pennsylvania, vol. 2}, booktitle = {2003 IEEE MTT-S International Microwave Symposium digest, June 8 - 13, 2003, Pennsylvania Convention Center, Philadelphia, Pennsylvania, vol. 2}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {0-7803-7695-1}, doi = {10.1109/MWSYM.2003.1212515}, pages = {903 -- 906}, abstract = {Coplanar W-band push-push VCO MMICs using GaInP/GaAs HBTs are presented. One circuit operates at 77 GHz with phase noise of -92 dBc/Hz at 1 MHz offset. To our knowledge this is the first fully monolithic W-band VCO with phase noise better than -90 dBc/Hz. A second version with two varactor diodes yields an almost threefold relative tuning bandwidth.}, language = {en} } @misc{SoniaRichterBrunneretal., author = {Sonia, G. and Richter, E. and Brunner, F. and Denker, A. and Lossy, R. and Mai, M. and Lenk, Friedrich and Bundesmann, J. and Pensl, G. and Schmidt, J. and Zeimer, U. and Wang, L. and Baskar, K. and Weyers, M. and W{\"u}rfl, Joachim and Tr{\"a}nkle, G{\"u}nther}, title = {2 MeV ion irradiation effects on AlGaN/GaN HFET devices}, series = {Solid-State Electronics}, volume = {52}, journal = {Solid-State Electronics}, number = {7}, issn = {0038-1101}, pages = {1011 -- 1017}, abstract = {AlGaN/GaN heterostructure field effect transistors (HFETs) were irradiated with 2 MeV protons, carbon, oxygen, iron and krypton ions with fluences ranging from 1 × 109 cm-2 to 1 × 1013 cm-2. DC, pulsed I-V characteristics, loadpull and S-parameters of the AlGaN HFET devices were measured before and after irradiation. In parallel, a thick GaN reference layer was also irradiated with the same ions and was characterized by X-ray diffraction, photoluminescence, Hall measurements before and after irradiation. Small changes in the device performance were observed after irradiation with carbon and oxygen at a fluence of 5 × 1010 cm-2. Remarkable changes in device characteristics were seen at a fluence of 1 × 1012 cm-2 for carbon, oxygen, iron and krypton irradiation. Similarly, remarkable changes were also observed in the GaN layer for irradiations with fluence of 1 × 1012 cm-2. The results found on devices and on the GaN layer were compared and correlated.}, language = {en} } @misc{GnanapragasamRichterBrunneretal., author = {Gnanapragasam, S. and Richter, E. and Brunner, F. and Denker, A. and Lossy, R. and Mai, M. and Lenk, Friedrich and Opitz-Coutureau, J. and Pensl, G. and Schmidt, J. and Zeimer, U. and Wang, L. and Krishnan, B. and Weyers, M. and W{\"u}rfl, Joachim and Tr{\"a}nkle, G{\"u}nther}, title = {Irradiation effects on AlGaN HFET devices and GaN layers}, series = {Journal of Materials Science: Materials in Electronics}, volume = {19}, journal = {Journal of Materials Science: Materials in Electronics}, number = {1}, issn = {1573-482X}, doi = {10.1007/s10854-008-9589-1}, pages = {64 -- 67}, abstract = {AlGaN/GaN heterostructure field effect transistors (HFETs) were irradiated with protons as well as carbon, oxygen, iron and krypton ions of high (68 and 120 MeV) and low (2 MeV) energy with fluences in the range from 1x107 to 1x1013 cm-2. High energy irradiation with protons, carbon and oxygen produced no degradation in devices while krypton irradiation at the fluence of 1x1010 cm-2 resulted in a small reduction of 2\% in the transconductance. Similarly, for GaN samples irradiated with protons, carbon and oxygen at high energy no changes were seen by XRD, PL and Hall effect, while changes in lattice constant and a reduction in PL intensity were observed after irradiation with high energy krypton. Low energy irradiation with carbon and oxygen at a fluence of 5x1010 cm-2 results in small change in the device performance while remarkable changes in device characteristics are seen at a fluence of 1x1012 cm-2 for carbon, oxygen, iron and krypton irradiation. Similarly changes are also observed by XRD, PL and Hall effect for the thick GaN layer irradiated at the fluence of 1x1012 cm-2. The device results and GaN layer properties are strongly correlated.}, language = {en} } @misc{SoniaRichterBrunneretal., author = {Sonia, G. and Richter, E. and Brunner, F. and Denker, A. and Lossy, R. and Lenk, Friedrich and Opitz-Coutureau, J. and Mai, M. and Schmidt, J. and Zeimer, U. and Wang, L. and Baskar, K. and Weyers, M. and W{\"u}rfl, Joachim and Tr{\"a}nkle, G{\"u}nther}, title = {High energy irradiation effects on AlGaN/GaN HFET devices}, series = {Semiconductor Science and Technology}, volume = {22}, journal = {Semiconductor Science and Technology}, number = {11}, issn = {0268-1242}, doi = {10.1088/0268-1242/22/11/007}, pages = {1220 -- 1224}, abstract = {The effect of proton, carbon, oxygen and krypton irradiation on AlGaN HFET devices has been studied. Irradiation was performed at 68 and 120 MeV with fluences in the range from 1 × 10^7 to 1 × 10^13 cm2 . Before and after irradiation, dc and pulsed I - V characteristics, loadpull and S -parameters of the AlGaN HFET devices were measured. A thick GaN reference layer was characterized by x-ray diffraction, photoluminescence and Hall measurements before and after irradiation. Proton, carbon and oxygen irradiation show no degradation in devices while krypton irradiation shows a small change at a fluence of 1 × 10 10 cm2 in the device characteristics. The device results are correlated with the thick GaN results.}, language = {en} } @inproceedings{HilsenbeckBrunnerLenketal., author = {Hilsenbeck, Jochen and Brunner, F. and Lenk, Friedrich and W{\"u}rfl, Joachim}, title = {Fabrication and Electrical Performance of Oscillators in GaAs/GaInP-HBT MMIC Technology up to 40 GHz}, series = {29th International Symposium on Compound Semiconductors (ISCS), Lausanne/Switzerland, 2002}, booktitle = {29th International Symposium on Compound Semiconductors (ISCS), Lausanne/Switzerland, 2002}, publisher = {Institute of Physics Publ.}, address = {Bristol [u.a.]}, isbn = {0-7503-0942-3}, pages = {239 -- 242}, language = {en} } @misc{YazdaniZervosBeleniotisetal., author = {Yazdani, Hossein and Zervos, Christos and Beleniotis, Petros and Brusaterra, Enrico and Hilt, Oliver and Rudolph, Matthias and W{\"u}rfl, Joachim}, title = {Importance of Scaling in RF GaN HEMTs for Reduction of Surface Traps-Induced Drain Lag}, series = {Physica Status Solidi (a)}, journal = {Physica Status Solidi (a)}, publisher = {Wiley}, issn = {1862-6300}, doi = {10.1002/pssa.202300885}, pages = {1 -- 8}, abstract = {Drain lag is a well-known phenomenon that leads to radio frequency performance degradation in AlGaN/GaN high-electron-mobility transistors. Herein, it is demonstrated that a reduction of the gate-to-drain distance (Lgd) from 2.0 to 0.5 μm results in 7\% reduction in the current collapse. This improvement is attributed to a decrease in surface trapping, which, in this case, is found to have a greater impact on current collapse than relatively slow traps in the buffer layer. To support this argument, TCAD simulations are conducted. Load-pull analysis confirms that scaling the devices to Lgd = 0.5 μm provides 15\% better output power density at 10 GHz than Lgd = 2.0 μm. Additionally, a new passivation layer for reduced surface traps exhibits a 20 to 30\% higher output power density and at least a 10\% improvement in power-added efficiency at 20 GHz on a nominally identical GaN-on-semi-insulating SiC epi-wafer.}, language = {en} } @misc{YazdaniBeleniotisBrunneretal., author = {Yazdani, Hossein and Beleniotis, Petros and Brunner, Frank and Ostermay, Ina and W{\"u}rfl, Joachim and Rudolph, Matthias and Heinrich, Wolfgang and Hilt, Oliver}, title = {K/Ka-Band-GaN-High-Electron-Mobility Transistors Technology with 700 mS mm-1 Extrinsic Transconductance}, series = {Physica Status Solidi}, journal = {Physica Status Solidi}, doi = {10.1002/pssa.202400592}, pages = {8}, language = {en} }