This paper critically investigates the advantages and limitations of the current-transient methods used for the study of the deep levels in GaN-based high-electron mobility transistors (HEMTs), by evaluating how the procedures adopted for measurement and data analysis can influence the results of the investigation. The article is divided in two parts within Part I. 1) We analyze how the choice of the measurement and analysis parameters (such as the voltage levels used to induce the trapping phenomena and monitor the current transients, the duration of the filling pulses, and the method used for the extrapolation of the time constants of the capture/emission processes) can influence the results of the drain current transient investigation and can provide information on the location of the trap levels responsible for current collapse. 2) We present a database of defects described in more than 60 papers on GaN technology, which can be used to extract information on the nature and origin of the trap levels responsible for current collapse in AlGaN/GaN HEMTs. Within Part II, we investigate how self-heating can modify the results of drain current transient measurements on the basis of combined experimental activity and device simulation
4.7 W continuous-wave (CW) and 11.7 W quasi-CW output power have been demonstrated for laser diodes based on six-fold stacks of InGaAs/GaAs quantum dots. Lifetimes beyond 3000 h at 1.0 and 1.5 W output power and 50degreesC heatsink temperature were measured. The output power is limited by catastrophic optical mirror damage occurring at 19.5 MW/cm(2) on the front facet
A metamorphic HEMT (MHEMT) MMIC technology including circuit applications is presented. The MHEMT layers are MBE grown on 4-inch GaAs wafers. The technology is based on a 50 nm gate length MHEMT and includes a 50 pm substrate backside process with dry etched through-substrate vias. For the electron confinement an InO8GaO2As/lnO53Ga047As composite channel was used. The devices are passivated with BCB and SiN to achieve a median time-to-failure of 2.7 x 1 06 h in air.Cut-off frequencies f, and fmax of 375 GHz were extrapolated for a 2 x 15 pm gate width device.Low-noise amplifiers with more than 1 5 dB gain in the frequency range from 192 GHz to 235 GHz were realized.
The facet heating of a single-quantum well InGaAs/AlGaAs broad-area high-power laser-diodes emitting at 940 nm was reduced by the introduction of a 30 µm long current blocking region located at the front facet of the laser, also increasing the level of catastrophical optical mirror damage. The blocking of the pump current close to the facet reduces the carrier density and then the surface recombination current. The temperature rise of 2 mm long and 200 µm wide lasers is reduced by a factor of 3-4
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