AlN/GaN insulated gate heterostructure FET with regrown n+GaN ohmic contact

Kawai, H.; Hara, Masaki; Nakamura, Fumihiko; Imanaga, Syunji

doi:10.1049/el:19980464

Cited by 59 publications

(26 citation statements)

References 6 publications

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“…An AlN/GaN insulated-gate heterojunction field effect transistor (HFET) was first reported by Kawai et al [16]. The lattice mismatch between AlN and GaN is about 2.5%, which results in the production of a large number of strain induced piezoelectric charges and spontaneous polarization charges at the AlN/GaN interface.…”

Section: New Approachesmentioning

confidence: 99%

Current status of GaN power devices

Kachi

2013

IEICE Electron. Express

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Abstract:The performance of GaN power devices has been rapidly improving. Recently, the main approach is the use of AlGaN/GaN HEMT structures on Si substrates, for which the target breakdown voltage is initially 600 V or less. Although issues still remain with regard to current collapse and the threshold voltage required for normallyoff operation, many companies have announced their intention to commercialize such devices. In this report, recent developments concerning GaN power devices are reviewed, and unresolved issues and future expectations are discussed.

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Section: New Approachesmentioning

confidence: 99%

Current status of GaN power devices

Kachi

2013

IEICE Electron. Express

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“…However, the devices displayed low transconductance (g m ) due to high-density interface states. Kawai and co-workers 11 have demonstrated good dc performance of the GaN IG FET using an epitaxial AlN layer as a gate dielectric. However, it is very difficult to suppress the leakage current through AlN because of the difficulty of growing high-quality AlN films.…”

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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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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“…AlN, with its relatively high dielectric constant (8.5) and wide bandgap (6.2 eV), has the potential to be an excellent choice for the gate dielectric in GaN-based MISFET devices. 4,5 The authors presented a first report on AlN/GaN MISFETs with promising electrical characteristics and very low interface-state density, proving the possibility of a high-quality AlN/GaN interface. 6,7 However, from the growth standpoint, it is difficult to grow high-quality AlGaN layers with high Al composition.…”

Section: Introductionmentioning

confidence: 99%

Metal-organic vapor phase epitaxy growth and characterization of AlN/GaN heterostructures

Hubbard

Pavlidis

Valiaev

et al. 2002

Journal of Elec Materi

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INTRODUCTIONElectronic devices based on the III-nitride group of materials (GaN, AlN, and InN) have recently shown great promise for high-frequency/high-power applications. For the most part, these devices are based on low Al-composition, AlGaN/GaN heterostructure field-effect transistors (HFETs). Metal-organic vapor-phase epitaxy (MOCVD) based AlGaN/ GaN FETs grown on sapphire substrates have shown room-temperature two-dimensional electron gas (2DEG) mobilities in excess of 1600 cm 2 /Vs, 1 while mobilities over 2000 cm 2 /Vs have been obtained using 6H-SiC substrates. 2 In addition, such devices have achieved power performance up to 9.1 W/mm at a frequency of 8.2 GHz. 3 However, these devices all use Schottky contacts as the gate barrier, which have not yet proven to be stable at high temperatures. In contrast, metal-insulator-semiconductor (MIS)-based FETs can use hightemperature stable insulators at the interface. The use of a gate insulator also allows the gate to be placed much closer to the channel, possibly leading to higher intrinsic transconductance. AlN, with its relatively high dielectric constant (8.5) and wide bandgap (6.2 eV), has the potential to be an excellent choice for the gate dielectric in 5 The authors presented a first report on AlN/GaN MISFETs with promising electrical characteristics and very low interface-state density, proving the possibility of a high-quality AlN/GaN interface. 6,7 However, from the growth standpoint, it is difficult to grow high-quality AlGaN layers with high Al composition. 8 The problems of lattice-mismatch (2.47% for AlN on GaN), prereactions between TMAl and NH 3 , and three-dimensional (3-D) growth must be overcome for effective high-quality AlN/GaNbased MISFET devices. Smorchkova et al. 9 have recently shown results for molecular-beam-epitaxygrown AlN/GaN structures with thin AlN barriers. In this paper, we present a systematic study of the impact of MOVPE growth parameters on the AlN/GaN material and the heterostructure formed between them. In addition, we have recently presented results using cathodoluminescence microanalysis to prove a correlation between 2DEG formation, interface scattering, and recombination processes at the AlN/GaN interface. 10 EXPERIMENTALThe GaN and AlN layers were grown by low-pressure (60-110 torr) MOVPE on c-plane (0001) sapphire substrates. The reactor was a custom-built, horizontal quartz-tube reactor connected to a modi-2.-Currently with IQE plc Head Office, St. Mellons, Cardiff CF3 0EG, United Kingdom Low-pressure, metal-organic vapor-phase epitaxy (MOVPE) was used to grow AlN/GaN metal-insulator-semiconductor (MIS) heterostructures with AlN thickness between 3 nm and 30 nm. The Hall mobility was found to decrease with increasing AlN thickness, with optimal mobility measured at 5-nm AlN. By decreasing the ammonia flow during AlN growth (lower V/III ratio), surface and interface quality were greatly improved with a corresponding improvement in electrical properties. For the optimal V/III ratio, room-temperature (RT) mobility and...

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AlN/GaN insulated gate heterostructure FET with regrown n+GaN ohmic contact

Cited by 59 publications

References 6 publications

Current status of GaN power devices

Current status of GaN power devices

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

Metal-organic vapor phase epitaxy growth and characterization of AlN/GaN heterostructures

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