Hot electron degradation of the DC and RF characteristics of AlGaAs/InGaAs/GaAs PHEMT's

Borgarino, M.; Menozzi, Roberto; Baeyens, Y.; Cova, Paolo; Fantini, Fausto

doi:10.1109/16.658668

Cited by 57 publications

(24 citation statements)

References 24 publications

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“…This dependence is very similar to what was observed in [46], thus confirming that a field-aided de-trapping mechanism is responsible for the change in VT. …”

Section: Effect Of Electric Fieldsupporting

confidence: 76%

“…This change was found to be mostly recoverable with unbiased storage at room temperature [23] and was independent of the stressing environment (the shift was the same, whether in air or in nitrogen). Negative shifts in VT have been previously observed in GaAs HEMTs under stress, though a wide variety of very different mechanisms have been proposed [5,10,12,21,46]. Although a hypothesis for the VT shift seen in our devices was proposed in [23], it was later discovered that some assumptions made about the relative levels of impact ionization in the devices studied were incorrect.…”

Section: Negative Vt Shiftmentioning

confidence: 75%

“…Instead, AVT seems to have a significant correlation with the peak electric field in the drain-gate region. This suggests that the de-trapping mechanism involves field-assisted tunneling of the electrons out of the traps, as mentioned in [46]. The de-trapping can be thermally activated [21], which explains how AVT is accelerated with increasing temperature.…”

Section: Discussionmentioning

confidence: 99%

“…Here there clearly seems to be a correlation between AVT and 1/Ld, suggesting that the VT shift is actually correlated with the peak electric field. This thus suggests a field-aided de-trapping mechanism, in which trapped electrons tunnel out of traps, as suggested in [46]. …”

Section: Negative Vr Shiftmentioning

confidence: 95%

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Electrical degradation mechanisms of RF power GaAs PHEMTs

Villanueva

Alamos

Hisaka³

et al.

IEEE International Electron Devices Meeting 2003

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GaAs Pseudomorphic High-Electron Mobility Transistors (PHEMTs) are widely used in RF power applications. Since these devices typically operate at high power levels and under high voltage biasing, their electrical reliability is of serious concern. Previous studies have identified several distinct degradation phenomena in these devices, but a complete picture has yet to be formed.In this study, we have carried out a comprehensive study of the mechanisms of electrical degradation on a set of experimental RF power GaAs PHEMTs (non-commercial devices provided by our sponsor, Mitsubishi Electric). A wide variety of electrical stressing experiments employing different conditions (varying temperature, bias, environment) were performed on these devices in order to monitor their degradation with stressing.Our general observations showed several forms of degradation, the most concerning being an increase in the drain resistance RD and a reduction in maximum drain current Ima. Contrary to what is often claimed in the literature, our experiments indicated that these forms of degradation were not driven by impact-ionization or hot-electron effects. Instead, we found the degradation to be strongly correlated with temperature, stressing environment, and drain-gate bias, which were all consistent with a corrosion mechanism. Via materials analysis we were able to confirm that the degradation of both RD and I,., were due to surface corrosion on the drain side of the device, albeit at different specific locations. The increase in RD was attributed to oxidation on the n+GaAs ledge, while the reduction in I, was due to oxidation on the AlGaAs surface, closer to the gate.A recoverable negative shift in the threshold voltage VT and a permanent decrease in Rs were also observed during electrical stressing. The shift in VT was attributed to field-assisted tunneling of electrons out of traps under the gate, while the decrease in Rs was found to be consistent with recombination-induced annealing of defects on the source side of the device.

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“…This dependence is very similar to what was observed in [46], thus confirming that a field-aided de-trapping mechanism is responsible for the change in VT. …”

Section: Effect Of Electric Fieldsupporting

confidence: 76%

Section: Negative Vt Shiftmentioning

confidence: 75%

Section: Discussionmentioning

confidence: 99%

Section: Negative Vr Shiftmentioning

confidence: 95%

See 2 more Smart Citations

Electrical degradation mechanisms of RF power GaAs PHEMTs

Villanueva

Alamos

Hisaka³

et al.

IEEE International Electron Devices Meeting 2003

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“…This layer has been reported to be of good quality in [19], the thickness should be small enough to have a good doping efficiency [38]. The effects of hot electrons have been previously described in [12], [39] , [40] and [41].…”

Section: Concentrationmentioning

confidence: 99%

Electrical degradation of InAlAs/InGaAs metamorphic high-electron mobility transistors

Mertens

Alamo²

International Electron Devices Meeting. Technical Digest (Cat. No.01CH37224)

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InAlAs/InGaAs metamorphic High Electron Mobility Transistors (HEMT) hold promise for power-millimeter wave applications. A major reliability concern in some of these devices is the degradation of the drain resistance that is observed when the device is electrically stressed for a long time at bias conditions necessary for power applications. The goal of this thesis was to find the physical origin of this reliability problem and to suggest solutions to it. State-of-the-art InAlAs/InGaAs metamorphic HEMTs, provided by our sponsor, Hewlett Packard, were stressed under different bias schemes. It was found that most figures of merit associated with the drain-side of the device degrade under severe bias stress. In particular, the drain resistance, RD, has been found to increase significantly. In order to understand the physical origin of this degradation, we have studied the degradation of simpler Transmission Line Model (TLM) structures. We have found that in TLMs and HEMTs there appear to be two different degradation modes, both associated with hot electrons. In the first degradation mechanisms, we postulate that hot electrons are trapped by defects at the interface between the GaAs etch-stopper and the AlInAs Schottky barrier layer, depleting the carrier concentration in the channel underneath. In the second mechanism hot electrons degrade the InGaAs ohmic contacts. No degradation mechanism associated with the metamorphic nature of the structure has been identified. AcknowledgementsI would like to thank Prof. Jesus del Alamo for giving me the chance to work on this interesting project. He has guided me through this research with a huge amount of patience, ideas and red ink, teaching me a methodology in research and reporting. He always tried to make time available for me, even if he was extremely busy. I would like to thank him for offering me the opportunity to be a teaching assistant for his very interesting class and for giving me a place at MIT from the time I arrived. This research has been funded by Hewlett-Packard. I would like to thank Don D'Avanzo for starting this project, appropriating the funding and giving me the opportunity to work as a SEED student in Santa Rosa. Larry Studebaker, thanks for the invaluable help and the samples during the year and the supervision this Summer. I am very happy that I have found such a great co-advisor. I had a great time in Santa Rosa and I learned a lot there, also thanks to Dan Scherrer, Fred Sughiwo and Bob Yeats. HP Labs also helped me a lot through this thesis. Hans Rohdin, thank you for answering so many questions, reading this thesis on time and sending me the samples that helped pull things together. Thanks to Arlene Wakita and Nick Moll for making these devices available to me.Roxann Blanchard, thanks for all the discussions we held and the questions you answered, even when you were busy with your own thesis. You have proven to be an infinite well of knowledge and I can only hope I have been able to soak up enough of it to continue this research.Tassan...

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