Observation of deep traps responsible for current collapse in GaN metal–semiconductor field-effect transistors

Klein, P. B.; Freitas, Jaime A.; Binari, S.C.; Wickenden, A. E.

doi:10.1063/1.125523

Cited by 182 publications

(111 citation statements)

References 15 publications

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“…2 for an MBE-grown HEMT after stress has been applied, and compared to a MESFET and a HEMT, both grown by MOCVD. The MOCVD devices both reflect the two broad absorption thresholds associated with trap1 and trap2 [3], as well as the expected rise at the GaN bandgap. The spectrum of the MBE device is quite different, exhibiting a broad trap1 absorption, no visible trap2 absorption threshold near 2.85 eV, and a new absorption threshold near 3.7 eV, above the GaN bandgap.…”

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confidence: 72%

“…Both traps have also been associated with persistent photoconductivity in GaN. Trap1 appears to be a strongly lattice-coupled deep donor [3,7] and trap2 has been identified [8] as a carbon-related defect.…”

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confidence: 99%

“…The subsequent trapping of these carriers leads to the reduced drain current. A technique that has been introduced recently to investigate the nature of the traps that cause current collapse is photoionisation spectroscopy [3]. In these measurements, a fully collapsed device, in which the deep traps have been filled, is illuminated with belowbandgap light.…”

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confidence: 99%

“…The dependence of the drain current increase on the incident photon energy maps out a photoionisation spectrum, which is an absorption spectrum that is characteristic of the deep defect and may be used to identify or 'tag' the defect. Previous photoionisation studies of nitride-based metal-semiconductor field effect transistors (MESFETs) [3][4][5] and high electron mobility transistors (HEMTs) [6] grown by metal organic chemical vapour deposition (MOCVD) have shown that two deep traps residing in the highresistivity (HR) GaN buffer layer are responsible for collapse in these devices. The two traps, labelled trap1 and trap2, introduce two broad, below-gap absorptions into the spectrum with photoionisation thresholds at 1.8 and 2.85 eV, respectively.…”

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confidence: 99%

“…We must conclude, therefore, that the 3.7 eV threshold does not appear to be associated with a deep centre that could result in current collapse, but instead corresponds to the photoneutralisation of ionised shallow acceptors. Since the trap1 defect and the 3.7 eV threshold were the only features in the photoionisation spectrum that could be associated with the collapse, it appears that the sole trapping centre that is responsible for stressinduced current collapse in MBE-grown HEMTs is trap1, a GaN buffer layer defect [3,4].…”

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confidence: 99%

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Photoionisation spectroscopy of traps in AlGaN/GaN high electron mobility transistors grown by molecular beam epitaxy

et al. 2003

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confidence: 72%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Photoionisation spectroscopy of traps in AlGaN/GaN high electron mobility transistors grown by molecular beam epitaxy

et al. 2003

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Modulation Doped FETs

Liu

Morkoç̌

2005

Encyclopedia of RF and Microwave Engineering

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Operation and technology of conventional and pseudomorphic modulation‐doped field‐effect transistors (MODFET s) based on conventional semiconductors, SiGe/Si heterostructures, and recently popularized III–V nitride semiconductors are treated. While conventional AlGaAs/GaAs MODFET represent the genesis of these highly successful devices, pseudomorphic MODFET s (PMODFET s) exhibit additional degrees of freedom in the choice of channel composition. This added degree of freedom has led to device structures that can be tailored to a particular application with significant improvement in performance. Experiments carried out with AlGaAs/InGaAs/GaAs and InAlAs/InGaAs/InP PMODFET s demonstrate that these devices are superior to their counterparts with lattice‐matched channels. MODFET s with unprecedented performance, for instance, with a power gain of 7.3 dB at 140 GHz and a noise level of 1.4 dB in the 90‐GHz range, are described. The advent of high‐quality SiGe layers on Si substrates has paved the way to the exploration and exploitation of heterostructure devices in a Si environment. MODFET s based on the Si/SiGe have been achieved with extraordinary p‐channel performance. With 0.25‐μm gate lengths, the current gain cutoff frequency is about 40 GHz. When the gate length was reduced to 0.1 μm, the current gain cutoff frequency increased to about 70 GHz. Finally, owing to their large bandgaps, large high field electron velocity, large breakdown fields, large thermal conductivity, and robustness, wide‐bandgap nitride semiconductors have paved the way to AlGaN/GaN MODFET s with superior power performance. CW power levels of about 6 W have been achieved at 10 GHz in devices with 1 mm gate periphery that are comparable to power densities extrapolated from smaller devices. When four of these devices were power combined in a single‐stage amplifier, a CW output power of 22.9 W with a power‐added efficiency of 37% was demonstrated at 9 GHz. On the noise figure front, a minimum noise figure for a 1‐mm device of 0.85 dB with an associated gain of 11 dB at 10 GHz was obtained.

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Bias Stress Measurements on High Performance AlGaN/GaN HFET Devices

Liu

Bardwell

McAlister

et al. 2001

phys. stat. sol. (a)

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High performance AlGaN/GaN heterojunction field effect transistor (HFET) devices have been fabricated, using material grown by MBE on sapphire substrates. The Hall effect 2DEG sheet charge densities and mobilities were as high as 1.68 Â 10 13 cm --2 and 1000 cm 2 /Vs respectively. Peak dc currents in excess of 1 A/mm, with transconductances in excess of 220 mS/mm were common. f T and f max scaled linearly with the inverse of the gate length, with maximum values of 39 and 80 GHz recorded for T-gates of length %0.3 mm. The devices with optically defined gates were stressed at V DS = 10 V and V G = 1 V, for times up to 5000 s. The stress decreased both f T and f max , but this degradation mostly recovered after a few days. In contrast, the gate leakage current improved (decreased) with stressing, but did not return to the initial undesirable levels. Thus, we found that electrical bias stressing can have a positive effect on some of the characteristics of our devices.

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Observation of deep traps responsible for current collapse in GaN metal–semiconductor field-effect transistors

Cited by 182 publications

References 15 publications

Photoionisation spectroscopy of traps in AlGaN/GaN high electron mobility transistors grown by molecular beam epitaxy

Photoionisation spectroscopy of traps in AlGaN/GaN high electron mobility transistors grown by molecular beam epitaxy

Modulation Doped FETs

Bias Stress Measurements on High Performance AlGaN/GaN HFET Devices

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