Surface leakage currents in SiN/sub x/ passivated AlGaN/GaN HFETs

Tan, W. S.; Uren, Michael J.; Houston, P.A.; Green, R.T.; Balmer, R.S.; Martin, T.

doi:10.1109/led.2005.860383

Cited by 110 publications

(71 citation statements)

References 18 publications

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“…Additionally, surfaces may have far more conductivity than the bulk, and defects may dominate the current flow mechanism (e.g., trap-to-trap hopping conduction). [341,342] A third legacy consideration is associated with the much higher internal electric fields supported by UWBG materials. Breakdown by other mechanisms is likely to occur before conventional impact-ionization-driven avalanche breakdown.…”

Section: Modeling/calibrationmentioning

confidence: 99%

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

Tsao

Chowdhury

Hollis

et al. 2017

Adv Elect Materials

980

463

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Section: Modeling/calibrationmentioning

confidence: 99%

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

Tsao

Chowdhury

Hollis

et al. 2017

Adv Elect Materials

980

463

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“…Actually, many researchers have reported that surface passivation might increase the surface leakage current even if the passivation effect has been confirmed. 30,31 We just want to show that surface leakage currents do exist and it will induce surfacetrap-related non-localized trapping effect. If the surface traps were reduced by the passivation, the corresponding nonlocalized trapping effect will be also suppressed.…”

Section: B Observation Of Surface Leakage Currentmentioning

confidence: 99%

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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“…For the untreated device, the activation energy is 0.33 eV, which is in good agreement with the low-bias Arrhenius plots of Figure 3 and the trap depths reported previously. [12][13][14] However, for the H 2 SO 4 treated device, the activation energy is very similar at low temperatures (0.3 eV) but increases significantly to 0.68 eV at high temperatures. This again highlights the fact that the H 2 SO 4 treatment has introduced some deep level traps in the surface states.…”

Section: -mentioning

confidence: 96%

“…[12][13][14] Note that there is a departure from the straight line at low temperatures. The reason for this is unclear but it may indicate the onset of the domination of states with much smaller activation energies.…”

Section: -mentioning

confidence: 97%

“…In order to measure the gate surface and bulk leakage (through the channel) components independently, a custom test structure incorporating a guard ring is used 12 as shown in Figure 2(a) and the results before and after the chemical treatmentsareshowninFigure2(b). It can be seen that compared to untreated devices, both H 2 SO 4 and H 2 O 2 treatments are effective in suppressing the gate surface leakage component as expected.…”

Section: -mentioning

confidence: 99%

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Sulfuric acid and hydrogen peroxide surface passivation effects on AlGaN/GaN high electron mobility transistors

Zaidi

Lee

Guiney

et al. 2014

Journal of Applied Physics

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In this work, we have compared SiNx passivation, hydrogen peroxide, and sulfuric acid treatment on AlGaN/GaN HEMTs surface after full device fabrication on Si substrate. Both the chemical treatments resulted in the suppression of device pinch-off gate leakage current below 1 μA/mm, which is much lower than that for SiNx passivation. The greatest suppression over the range of devices is observed with the sulfuric acid treatment. The device on/off current ratio is improved (from 104–105 to 107) and a reduction in the device sub-threshold (S.S.) slope (from ∼215 to 90 mV/decade) is achieved. The sulfuric acid is believed to work by oxidizing the surface which has a strong passivating effect on the gate leakage current. The interface trap charge density (Dit) is reduced (from 4.86 to 0.90 × 1012 cm−2 eV−1), calculated from the change in the device S.S. The gate surface leakage current mechanism is explained by combined Mott hopping conduction and Poole Frenkel models for both untreated and sulfuric acid treated devices. Combining the sulfuric acid treatment underneath the gate with the SiNx passivation after full device fabrication results in the reduction of Dit and improves the surface related current collapse.

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Surface leakage currents in SiN/sub x/ passivated AlGaN/GaN HFETs

Cited by 110 publications

References 18 publications

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

Ultrawide‐Bandgap Semiconductors: Research Opportunities and Challenges

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

Sulfuric acid and hydrogen peroxide surface passivation effects on AlGaN/GaN high electron mobility transistors

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