Articles you may be interested in Effect of proton irradiation on thermal resistance and breakdown voltage of InAlN/GaN high electron mobility transistors J.

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Record RF performance of AlGaN/GaN high electron mobility transistors (HEMTs) on a diamond substrate with over 7 W/mm output power density at 10 GHz is reported. It is achieved along with the peak power‐added‐efficiency over 46% and power gain over 11 dB for 2 × 100 µm gate‐width HEMTs at 40 V drain bias. Device wafers are prepared by first removing the host Si (111) substrate and nitride transition layers beneath the channel, depositing a 50 nm dielectric onto the exposed GaN buffer, and finally growing 100 µm of a chemical vapour deposition diamond onto the dielectric adhering to the epitaxial AlGaN/GaN. This approach enables the active GaN channel to be brought within 1 µm of the diamond substrate. Test HEMTs are fabricated using a dielectrically defined 0.25 µm gate length process.

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Articles you may be interested inStructural, morphological, and defect properties of metamorphic In0.7Ga0.3As/GaAs0.35Sb0.65 p-type tunnel field effect transistor structure grown by molecular beam epitaxy Material properties and performance of metamorphic optoelectronic integrated circuits grown by molecular beam epitaxy on GaAs substrates Metamorphic heterojunction bipolar transistor ͑M-HBT͒ structures and metamorphic P -I -N (M-PIN) photodiode structures were grown on GaAs substrates. A compositionally graded AlGaInAs buffer layer was used to expand the lattice constant to that of InP. Cross-sectional transmission electron micrographs of the M-HBT structure showed that the dislocations from compositional grading were predominantly localized in the buffer layer and that the device layers possessed planar interfaces. Secondary ion mass spectroscopy depth profiles of the 4ϫ10 19 cm Ϫ3 beryllium-doped In 0.53 Ga 0.47 As base layer exhibited sharp doping interfaces, indicating that metamorphic growth was not causing enhanced beryllium diffusion. The current gain of large emitter M-HBT devices approached the current gain for the same device structure grown on an InP substrate. A P -I -N photodiode structure was also grown metamorphically on a GaAs substrate and lattice matched on an InP substrate. Both types of photodiodes showed almost identical responsivities and bandwidths. A responsivity to 1.55 m radiation of 0.55 A/W, which corresponds to an external quantum efficiency of 44%, was obtained with M-PIN photodiodes. The 3 dB bandwidths exceeded 20 GHz for M-PIN photodiodes with diameters of 25 m or smaller. These results are very encouraging for the application of metamorphic technology to nonmajority carrier devices.

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