Influence of MgO and Sc2O3 passivation on AlGaN/GaN high-electron-mobility transistors

Luo, B.; Johnson, J. W.; Kim, J.; Mehandru, R.; Ren, Fangfang; Gila, B. P.; Onstine, A. H.; Abernathy, C. R.; Pearton, S. J.; Baca, Albert G.; Briggs, Ronald D.; Shul, R. J.; Monier, C.; Han, Jung

doi:10.1063/1.1455692

Cited by 170 publications

(98 citation statements)

References 27 publications

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“…On the other The current collapse effects have often been observed GaN/AlGaN SG HFETs under quiescent gate stress 19 or pulse-mode gate stress. 17,18,24,37 The collapse is also induced by drain stress. 1,18,37 The mechanism for the current collapse is not clarified yet.…”

Section: Application Of the Al 2 O 3 -Based Passivation Structure mentioning

confidence: 99%

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Surface passivation of GaN and GaN/AlGaN heterostructures by dielectric films and its application to insulated-gate heterostructure transistors

Hashizume

Ootomo

Inagaki

et al. 2003

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

219

170

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We have systematically investigated effects of plasma processing, formation of Si-based dielectrics, and formation of a thin Al 2 O 3 film on the chemical and electronic properties of GaN and GaN/ AlGaN heterostructure surfaces. The surface treatment in H 2 -plasma excited by electron-cyclotron-resonance ͑ECR͒ source, produced nitrogen-vacancy-related defect levels at GaN and AlGaN surfaces, while the ECR-N 2 -plasma treatment improved electronic properties of the surfaces. The deposition of a SiO 2 film on GaN and AlGaN surfaces was found to induce high-density interface states, due to unexpected and uncontrollable oxidation reactions on the surfaces during the deposition process. In comparison, the SiN x /GaN passivation structure prepared by ECR-plasma assisted chemical vapor deposition showed good interface properties with the minimum D it value of 1ϫ10 11 cm Ϫ2 eV Ϫ1 . However, excess leakage currents governed by FowlerNordheim tunneling were observed in the SiN x /Al 0.3 Ga 0.7 N structure, due to a relatively small conduction band offset of 0.7 eV between SiN x and Al 0.3 Ga 0.7 N. A novel Al 2 O 3 -based passivation structure was proposed and fabricated by molecular beam deposition of Al and subsequent ECR O 2 -plasma oxidation. In situ x-ray photoelectron spectroscopy showed successful formation of the Al 2 O 3 layer with a thickness of 3.5 nm and a large conduction band offset of 2.1 eV between Al 2 O 3 and A 0.3 Ga 0.7 N. The GaN/AlGaN insulated-gate heterostructure field-effect transistors ͑IG HFETs͒ having the Al 2 O 3 -based passivation structure showed a good gate control of drain currents up to V GS ϭϩ3 V and achieved drain saturation current of 0.8 A/mm. The observed maximum g m value is 120 mS/mm. No current collapse was observed in the Al 2 O 3 IG HFETs, indicating a remarkable advantage of the present Al 2 O 3 -based passivation structure.

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Section: Application Of the Al 2 O 3 -Based Passivation Structure mentioning

confidence: 99%

“…Inoue and co-workers 23 fabricated the IG AlGaN/GaN HFET using native oxide of AlGaN itself formed by thermal oxidation at 900°C. Luo et al 24 reported the passivation effects of the MBE-grown MgO films on the AlGaN/GaN HFETs.…”

Section: Introductionmentioning

confidence: 99%

Surface passivation of GaN and GaN/AlGaN heterostructures by dielectric films and its application to insulated-gate heterostructure transistors

Hashizume

Ootomo

Inagaki

et al. 2003

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

219

170

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“…9 The current collapse effects have often been observed AlGaN/GaN HFETs under quiescent gate stress 10 or pulsemode gate stress. 11,12 The collapse is also induced by drain stress. 13,14 Hasegawa and coworkers 5 explained that the charging effects of the surface electronic states, consisting of a U-shaped surface state continuum and V N -related nearsurface deep donor, play a dominant role for the current collapse, 5 as schematically shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Lateral tunneling injection and peripheral dynamic charging in nanometer-scale Schottky gates on AlGaN/GaN hetrosturucture transistors

Kotani¹,

Kasai²,

Hashizume³

et al. 2005

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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The gate leakage and gate control characteristics of AlGaN/GaN heterostructure field effect transistors ͑HFETs͒ were systematically investigated in an attempt to clarify possible effects of surface states. The experiments were compared to rigorous computer simulations. We observed large amounts of leakage currents in the Schottky diodes fabricated on the AlGaN epitaxial layers. By the calculation based on a thin surface barrier model in which the effects of surface defect donor were taken into account, this large leakage was well explained by enhancement of tunneling transport processes due to the barrier thinning associated with ionization of surface-defect donor. On the other hand, the analysis on the current-voltage characteristics for the nanometer-scale Schottky contacts on AlGaN/GaN HFETs, indicated additional lateral leakage components. The comparison of the gate control characteristics between experiment and calculation clearly showed that the effective lateral expansion of gate length significantly impeded the g m enhancement by the reduction of geometrical gate length. This can be explained by the lateral electron tunneling process at the AlGaN surface stimulated by the pronounced gate leakage currents. Due to frequent tunneling transfer at the gate periphery, surface state occupancy near the gate becomes governed by the metal Fermi level, causing the dynamic surface state charging effects. This resulted in effective widening of the gate length, leading to degradation of gate control performance in AlGaN/GaN HFETs.

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“…Scandium oxide has attractive band gap and thermal lattice properties for use on GaN. 5 A Sc 2 O 3 layer was shown to effectively mitigate the collapse in drain current through passivation of the surface traps. 5,6 Additionally, it was demonstrated that Sc 2 O 3 can be used simultaneously as a gate oxide and as a surface passivation layer for AlGaN/GaN high electron mobility transistors.…”

Section: Introductionmentioning

confidence: 99%

“…5 A Sc 2 O 3 layer was shown to effectively mitigate the collapse in drain current through passivation of the surface traps. 5,6 Additionally, it was demonstrated that Sc 2 O 3 can be used simultaneously as a gate oxide and as a surface passivation layer for AlGaN/GaN high electron mobility transistors. 7 However, the gate oxide material must satisfy several criteria: in addition to the electronic function of a gate dielectric, the gate oxide material must maintain a high dielectric constant, and serve as a diffusion barrier against diffusion of material from the top electrode.…”

Section: Introductionmentioning

confidence: 99%

Metal diffusion properties of ultra-thin high-k Sc₂O₃ films

et al. 2017

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Influence of MgO and Sc2O3 passivation on AlGaN/GaN high-electron-mobility transistors

Cited by 170 publications

References 27 publications

Surface passivation of GaN and GaN/AlGaN heterostructures by dielectric films and its application to insulated-gate heterostructure transistors

Surface passivation of GaN and GaN/AlGaN heterostructures by dielectric films and its application to insulated-gate heterostructure transistors

Lateral tunneling injection and peripheral dynamic charging in nanometer-scale Schottky gates on AlGaN/GaN hetrosturucture transistors

Metal diffusion properties of ultra-thin high-k Sc₂O₃ films

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Influence of MgO and Sc2O3 passivation on AlGaN/GaN high-electron-mobility transistors

Cited by 170 publications

References 27 publications

Surface passivation of GaN and GaN/AlGaN heterostructures by dielectric films and its application to insulated-gate heterostructure transistors

Surface passivation of GaN and GaN/AlGaN heterostructures by dielectric films and its application to insulated-gate heterostructure transistors

Lateral tunneling injection and peripheral dynamic charging in nanometer-scale Schottky gates on AlGaN/GaN hetrosturucture transistors

Metal diffusion properties of ultra-thin high-k Sc2O3 films

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Metal diffusion properties of ultra-thin high-k Sc₂O₃ films