High transconductance enhancement-mode AlGaN∕GaN HEMTs on SiC substrate

Kumar, V.; Kuliev, A.; Tanaka, Tsuyoshi; Otoki, Yohei; Adesida, I.

doi:10.1049/el:20031124

Cited by 90 publications

(42 citation statements)

References 6 publications

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“…• C, which is needed to recover damages induced by chlorine-based ICP-RIE in the case of recessedgate [16], [19], this lower RTA temperature implies that the CF 4 plasma treatment creates lower damages than the chlorinebased ICP-RIE. It also enables the RTA process to be carried out after the gate deposition, fulfilling the goal of a self-aligned process.…”

Section: B Recovery Of Plasma-induced Damages By Post-gate Annealingmentioning

confidence: 99%

See 1 more Smart Citation

Control of Threshold Voltage of AlGaN/GaN HEMTs by Fluoride-Based Plasma Treatment: From Depletion Mode to Enhancement Mode

Cai

Zhou

Lau

et al. 2006

IEEE Trans. Electron Devices

504

286

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Section: B Recovery Of Plasma-induced Damages By Post-gate Annealingmentioning

confidence: 99%

“…• C was found to be able to repair the damages [16], [19]. However, the RTA at such high temperatures will not be compatible with the gate metal (Ni/Au, for example) and has to be carried out prior to the gate deposition.…”

Section: Introductionmentioning

confidence: 99%

Control of Threshold Voltage of AlGaN/GaN HEMTs by Fluoride-Based Plasma Treatment: From Depletion Mode to Enhancement Mode

Cai

Zhou

Lau

et al. 2006

IEEE Trans. Electron Devices

504

286

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“…This indicated that the band bending at the AlGaN surface due to the Fermi level pinning could be reduced by the Al 2 O 3 passivation [16], thereby increasing the 2DEG density at zero bias. [21] also reported high g m and drain current values in the normally-off mode HFET fabricated by using a gaterecessing process. However, the sweeping range of gate voltage in those devices was limited below +2 V due to the serious leakage currents through the Schottky gates.…”

mentioning

confidence: 81%

Al₂O₃ Insulated-Gate Structure for AlGaN/GaN Heterostructure Field Effect Transistors Having Thin AlGaN Barrier Layers

Hashizume

Anantathanasarn

Negoro

et al. 2004

Jpn. J. Appl. Phys.

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Although significant progress has been achieved in the GaN-based high-power/high-frequency electronic devices such as AlGaN/GaN heterostructure field effect transistors (HFETs) [1][2][3], it is necessary to use thinner AlGaN layer for achieving higher transconductance (g m ) and more precise control of threshold voltage in HFETs. To develop normally-off (enhancement) mode devices which are attractive for gaining in flexibility of circuit and/or system design, in addition, very thin AlGaN barrier thickness less than 10nm is required. A gate-recessing process is one of the actual approaches to reduce the effective thickness of a barrier layer.However, Schottky contacts fabricated on GaN and AlGaN still suffer from serious leakage problems [4][5][6][7][8][9]. Although some models associated with the trap-assisted tunneling [10], the defect-related thin surface barrier (TSB) [8] and the dislocation-related hopping transport [11] have been proposed, the leakage mechanism through GaN and AlGaN Schottky interfaces has not yet been clarified, and thereby there is still no solution to suppress leakage currents. For Schottky-gate (SG) structures on AlGaN/GaN HEMTs with thinner AlGaN barrier layers or recessed-gate structures, leakage problems can be enhanced, making the gate control of drain current very difficult.An FET device having an insulated gate (IG) structure is expected to suppress the gate leakage. Moreover, an insulator film can act as a passivation layer, making the surface more stable in the device. An Al 2 O 3 IG structure is very attractive for the application to AlGaN/GaN HFETs [12][13][14], since it has relatively high dielectric constant (~ 9) and a large conduction-band offset at the Al 2 O 3 /AlGaN interface [12]. In fact, the Al 2 O 3 IG AlGaN/GaN HFETs exhibited good gate control of drain current with low leakage currents, and suppressed current collapse under both drain stress and gate stress [12].In this letter, we demonstrate the controllability of an Al 2 O 3 insulated-gate structure in the AlGaN/GaN HFETs having a thin AlGaN barrier layer (7 nm).The Al 0.2 Ga 0.8 N/GaN heterostructures was grown by metal organic vapor phase epitaxy on n-type 6H-SiC substrates, as schematically shown in Fig.1. A very thin AlGaN layer (7 nm) was grown with doping of Si (2 x 10 18 cm -3 ). The electron concentration and mobility of the sample at room temperature (RT) were 4.0 x 10 12 cm -2 and 830 cm 2 /Vs, respectively. The device isolation was carried out by an electron-cyclotron-resonance (ECR) assisted reactive ion beam etching using a gas system consisting of CH 4 , H 2 , Ar and N 2 [15]. As an ohmic contact, a Ti/Al/Ti/Au layered structure was formed on the surface of AlGaN/GaN followed by annealing at 800 o C for 1 min in N 2 ambient. A Ni/Au contact was used as a Schottky gate.The Al 2 O 3 -based surface passivation structure was fabricated through the following in-situ steps [16]: The AlGaN surface was treated in ECR-N 2 plasma at 280 o C for 30 s. Then an Al layer with a nominal thickness of 3 nm was depo...

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“…This structure was made use of a thin AlGaN in order to obtain a shallow depletion region. It was also reported enhancement-mode HFETs using a recess gate structure [10], but the drain current at V gs =0 V was slightly flowed, resulting in an incomplete normally-off operation. The other method to realize the enhancement-mode operation is such as an isolated gate structure.…”

Section: Introductionmentioning

confidence: 94%

573 K operation AlGaN/GaN HFET with enhancement operation on Si substrate

Yoshida

Ikeda

2005

phys. stat. sol. (c)

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A normally-off FET is necessary for switching devices. We report on the enhancement operation GaNbased heterojunction field effect transistors (HFETs). The AlGaN/AlN/GaN heterostructure on a Si (111) substrate was grown using a metalorganic chemical vapor deposition (MOCVD). The HFET for a normally-off operation was fabricated using the AlGaN/C-GaN heterostructure. As a result, the HFET was operated at the condition of the positive gate bias. The breakdown voltage of FET was over 350 V. The onstate resistance (R on ) was about 10 mohmcm 2 . The maximum operation current of the FET was over 10 A. We also confirmed that the normally-off HFET was operated at 573 K. The normally-off operation of AlGaN/GaN HFETs on the Si substrate was thus confirmed for the first time.

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High transconductance enhancement-mode AlGaN∕GaN HEMTs on SiC substrate

Cited by 90 publications

References 6 publications

Control of Threshold Voltage of AlGaN/GaN HEMTs by Fluoride-Based Plasma Treatment: From Depletion Mode to Enhancement Mode

Control of Threshold Voltage of AlGaN/GaN HEMTs by Fluoride-Based Plasma Treatment: From Depletion Mode to Enhancement Mode

Al₂O₃ Insulated-Gate Structure for AlGaN/GaN Heterostructure Field Effect Transistors Having Thin AlGaN Barrier Layers

573 K operation AlGaN/GaN HFET with enhancement operation on Si substrate

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High transconductance enhancement-mode AlGaN∕GaN HEMTs on SiC substrate

Cited by 90 publications

References 6 publications

Control of Threshold Voltage of AlGaN/GaN HEMTs by Fluoride-Based Plasma Treatment: From Depletion Mode to Enhancement Mode

Control of Threshold Voltage of AlGaN/GaN HEMTs by Fluoride-Based Plasma Treatment: From Depletion Mode to Enhancement Mode

Al2O3 Insulated-Gate Structure for AlGaN/GaN Heterostructure Field Effect Transistors Having Thin AlGaN Barrier Layers

573 K operation AlGaN/GaN HFET with enhancement operation on Si substrate

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Al₂O₃ Insulated-Gate Structure for AlGaN/GaN Heterostructure Field Effect Transistors Having Thin AlGaN Barrier Layers