Integrated Optical and Electrical Analysis: Identifying Location and Properties of Traps in AlGaN/GaN HEMTs During Electrical Stress

Ťapajna, M.; Simms, R.; Pei, Yutao; Mishra, Umesh K.; Kuball, Martin

doi:10.1109/led.2010.2047092

Cited by 128 publications

(94 citation statements)

References 14 publications

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“…The hot electrons there are referred to as non-localized hot electrons hereafter. The existence of non-localized hot electrons has also been experimentally demonstrated by Tapajna et al 33 They found that the electron temperature is much higher than the lattice temperature across the entire drain access region for their AlGaN/GaN HFETs in the on-state.…”

Section: B Observation Of Surface Leakage Currentmentioning

confidence: 70%

Non-localized trapping effects in AlGaN/GaN heterojunction field-effect transistors subjected to on-state bias stress

Hu¹,

Hashizume²

2012

Journal of Applied Physics

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Evidence of space charge limited flow in the gate current of AlGaN/GaN high electron mobility transistors Appl. Phys. Lett. 100, 223504 (2012) Off-state breakdown and dispersion optimization in AlGaN/GaN heterojunction field-effect transistors utilizing carbon doped buffer Appl. Phys. Lett. 100, 223502 (2012) Charge transport and trap characterization in individual GaSb nanowires J. Appl. Phys. 111, 104515 (2012) The asymmetrical degradation behavior on drain bias stress under illumination for InGaZnO thin film transistors Appl. Phys. Lett. 100, 222901 (2012) Mechanism of random telegraph noise in junction leakage current of metal-oxide-semiconductor field-effect transistor J. Appl. Phys. 111, 104513 (2012) Additional information on J. Appl. Phys. For AlGaN/GaN heterojunction field-effect transistors, on-state-bias-stress (on-stress)-induced trapping effects were observed across the entire drain access region, not only at the gate edge. However, during the application of on-stress, the highest electric field was only localized at the drain side of the gate edge. Using the location of the highest electric field as a reference, the trapping effects at the gate edge and at the more distant access region were referred to as localized and non-localized trapping effect, respectively. Using two-dimensional-electron-gas sensing-bar (2DEG-sensing-bar) and dual-gate structures, the non-localized trapping effects were investigated and the trap density was measured to be $1.3 Â 10 12 cm À2 . The effect of passivation was also discussed. It was found that both surface leakage currents and hot electrons are responsible for the non-localized trapping effects with hot electrons having the dominant effect. Since hot electrons are generated from the 2DEG channel, it is highly likely that the involved traps are mainly in the GaN buffer layer. Using monochromatic irradiation (1.24-2.81 eV), the trap levels responsible for the non-localized trapping effects were found to be located at 0.6-1.6 eV from the valence band of GaN. Both trap-assisted impact ionization and direct channel electron injection are proposed as the possible mechanisms of the hot-electron-related non-localized trapping effect. Finally, using the 2DEG-sensing-bar structure, we directly confirmed that blocking gate injected electrons is an important mechanism of Al 2 O 3 passivation. V C 2012 American Institute of Physics.

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Section: B Observation Of Surface Leakage Currentmentioning

confidence: 70%

Non-localized trapping effects in AlGaN/GaN heterojunction field-effect transistors subjected to on-state bias stress

Hu¹,

Hashizume²

2012

Journal of Applied Physics

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“…Measurement was performed in a temperature range between 25 and 150˝C using a heated plate and an ATT Systems A150 temperature controller. (e.g., [14,17,20,21]) and between 0.71 and 0.82 eV (e.g., [1,9,19,[22][23][24]) were the most commonly reported. Unfortunately, their origin remains ambiguous.…”

Section: Methodsmentioning

confidence: 99%

Trapping Analysis of AlGaN/GaN Schottky Diodes via Current Transient Spectroscopy

et al. 2016

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Trapping effects on two AlGaN/GaN Schottky diodes with a different composition of the AlGaN barrier layer were analyzed by current transient spectroscopy. The current transients were measured at a constant bias and at six different temperatures between 25 and 150˝C. Obtained data were fitted by only three superimposed exponentials, and good agreement between the experimental and fitted data was achieved. The activation energy of dominant traps in the investigated structures was found to be within 0.77-0.83 eV. This nearly identical activation energy was obtained from current transients measured at a reverse bias of´6 V as well as at a forward bias of+1 V. It indicates that the dominant traps might be attributed to defects mainly associated with dislocations connected predominantly with the GaN buffer near the AlGaN/GaN interface.

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“…4 However, electroluminescence (EL) studies still show the appearance of degradation-related hot spots, under harsher stress conditions, at the drain side of the gate edge following OFF-state stress-tests. [5][6][7] Low frequency 1/f noise was proven to be a useful tool for reliability studies of AlGaN/GaN HEMTs. 8 Early work revealed higher noise in GaN HEMTs than AlGaAs/GaAs devices due to the larger density of native defects.…”

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confidence: 99%

Localization of off-stress-induced damage in AlGaN/GaN high electron mobility transistors by means of low frequency 1/f noise measurements

Silvestri

Uren

Killat

et al. 2013

Applied Physics Letters

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The location of the time dependent degradation in OFF-state stressed AlGaN/GaN high electron mobility transistors is studied using low frequency 1/f noise measurements, with additional electroluminescence analysis. The gate bias dependence of the 1/f noise is shown to be a powerful tool to illustrate that in addition to the gate edge breakdown, progressive time-dependent trap generation occurs underneath the gate area, possibly extending in the gate-drain access region due to the electric field peak associated with the gate field plate.Keywords: AlGaN/GaN HEMT, 1/f noise, reliability, OFF-state stress, Electroluminescence. a) Electronic mail: Marco.Silvestri@bristol.ac.uk 2 AlGaN/GaN high electron mobility transistors (HEMTs) are considered to be of high potential for high power, high voltage applications. The ever-increasing power demand in radio frequency, industrial, and automotive fields is key for these devices that exhibit both high mobility and breakdown voltage. 1 Charge trapping, material defects, current collapse, and gate degradation are among the main challenges and sources of failure in GaN-based HEMTs. 3 Above all, the gate breakdown is still a limiting factor for achieving long-term reliability at high operative voltages. In this framework, the introduction of field plates and engineered gate shapes significantly mitigated current collapse and reduced gate breakdown occurence. 4 However, electroluminescence (EL) studies still show the appearance of degradation-related hot spots, under harsher stress conditions, at the drain side of the gate edge following OFF-state stress-tests. [5][6][7] Low frequency 1/f noise was proven to be a useful tool for reliability studies of AlGaN/GaN HEMTs. 8 Early work revealed higher noise in GaN HEMTs than AlGaAs/GaAs devices due to the larger density of native defects. 9 The relatively high gate leakage current exhibited by Schottky-gate GaN HEMTs is also one of the main limiting factor which can contribute to the channel noise. 10 However, recent material advances and the reduction of surface and barrier defects have improved the noise performance of AlGaN/GaN HEMTs. 11Electronic generation-recombination trap states close to the Fermi level can be effectively measured based on low frequency noise and used to extract trap characteristics, such as activation energy, capture cross section, and trap density, as well as monitor device degradation during reliability tests. 12,13 The gate voltage dependence of the normalized noise spectral density was reported by other authors to be applicable to GaAs and GaN devices, demonstrating the ability to isolate the effect of noise in different areas of the device channel.To date, this approach has not been used to benefit the understanding of device damage during reliability tests. 3In this letter, the gate voltage and drain current dependences of the 1/f low frequency noise and EL signal are shown to be of great benefit to monitor and localize the damage in different parts of the GaN HEMT channel during OFF-state stress te...

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Integrated Optical and Electrical Analysis: Identifying Location and Properties of Traps in AlGaN/GaN HEMTs During Electrical Stress

Cited by 128 publications

References 14 publications

Non-localized trapping effects in AlGaN/GaN heterojunction field-effect transistors subjected to on-state bias stress

Non-localized trapping effects in AlGaN/GaN heterojunction field-effect transistors subjected to on-state bias stress

Trapping Analysis of AlGaN/GaN Schottky Diodes via Current Transient Spectroscopy

Localization of off-stress-induced damage in AlGaN/GaN high electron mobility transistors by means of low frequency 1/f noise measurements

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