Comparison of characteristics of AlGaN channel HEMTs formed on SiC and sapphire substrates

Nanjo, Takuma; Suita, Muneyoshi; Oishi, Toshiyuki; Abe, Yuji; Yagyu, Eiji; Yoshiara, Kiichi; Tokuda, Yasunori

doi:10.1049/el.2009.0129

Cited by 19 publications

(24 citation statements)

References 5 publications

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“…AlGaN/GaN high‐electron‐mobility transistors (HEMTs) are a promising candidate for the next generation of high‐frequency 1, 2 and electrical power device applications 3 owing to the wide band‐gap semiconductor properties of GaN. Several attempts to use AlGaN as a channel material instead of GaN, by taking advantage of the wider band‐gap semiconductor properties of AlGaN, have been reported 4–10. By employing AlGaN as the channel layer, advantages such as the enhancement of the breakdown voltage and stable operation at high temperature can be expected.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of two‐dimensional electron gases in AlGaN‐channel high‐electron‐mobility transistors with AlN barrier layers

Hashimoto

Akita

Yamamoto

et al. 2012

Physica Status Solidi (a)

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We have demonstrated a high sheet carrier concentration in AlGaN-channel high-electron-mobility transistors (HEMTs) with AlN barrier layer. We investigate the epitaxial structure of these HEMTs by X-ray diffraction and reveal that the partial lattice relaxation occurs in the Al 0.51 GaN-channel layers on the AlN buffer layers, and that the AlN barrier layer was coherently grown on the AlGaN channel layer. The sheet carrier concentration due to two-dimensional electron gases of the AlN/Al 0.51 GaN HEMT is 2.8 Â 10 13 cm À2 , which is enhanced owing to the use of AlN as the barrier layer. This value of the sheet carrier concentration agrees with the calculated value based on the model of partial lattice relaxation in AlGaN channel layer.

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Section: Introductionmentioning

confidence: 99%

Enhancement of two‐dimensional electron gases in AlGaN‐channel high‐electron‐mobility transistors with AlN barrier layers

Hashimoto

Akita

Yamamoto

et al. 2012

Physica Status Solidi (a)

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“…T. Nanjo et al [3] presented the AlGaN channel HEMTs on sapphire for the first time. In addition, AlGaN channel HEMTs on SiC [11] and AlN [7] substrates were also successively fabricated. To promote crystal quality and increase electron mobility of Al x Ga 1Àx N/ Al y Ga 1Ày N heterostructure, our research group proposed AlGaN channel HEMTs with a graded buffer layer, which effectively promote the saturation drain current from 218 to 540 mA/mm [9,10].…”

Section: Introductionmentioning

confidence: 99%

AlGaN channel MIS-HEMTs with a very high breakdown electric field and excellent high-temperature performance

Zhang

et al. 2015

IEICE Electron. Express

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We report on AlGaN channel metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) for the first time. The insulator of 10-nm SiN x was deposited by plasma enhanced chemical vapor deposition, which induced a low reverse and forward Schottky leakage. A very high breakdown electric field of 1.8 MV/cm was reached with a gatedrain distance of 2 µm. The breakdown voltage increased non-linearly with the gate-drain distance and reached 1661 V with a gate-drain distance of 20 µm. As temperature increases from 25 to 275°C, the saturation drain current decreases slightly by 20% from 211 to 169 mA/mm and the onresistance increases only by 24%.

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“…4,[8][9][10][11][12][13][14] Of all of these approaches, the planar, non-implanted contacts are the simplest to fabricate. A literature summary [4][5][6][14][15][16] of AlGaN HEMT contact metallurgy and the Al-fraction of the barrier and channel layers is listed in Table I. The specific contact resistance is plotted against the Al-fraction of both the barrier (Fig.…”

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confidence: 99%

Planar Ohmic Contacts to Al_0.45Ga_0.55N/Al_0.3Ga_0.7N High Electron Mobility Transistors

Klein

Baca

Armstrong

et al. 2017

ECS J. Solid State Sci. Technol.

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We present a low resistance, straightforward planar ohmic contact for Al 0.45 Ga 0.55 N/Al 0.3 Ga 0.7 N high electron mobility transistors. Five metal stacks (a/Al/b/Au; a = Ti, Zr, V, Nb/Ti; b = Ni, Mo, V) were evaluated at three individual annealing temperatures (850, 900, and 950 • C). The Ti/Al/Ni/Au achieved the lowest specific contact resistance at a 900 • C anneal temperature. Transmission electron microscopy analysis revealed a metal-semiconductor interface of Ti-Al-Au for an ohmic (900 • C anneal) and a Schottky (850 • C anneal) Ti/Al/Ni/Au stack. HEMTs were fabricated using the optimized recipe with resulting contacts that had room-temperature specific contact resistances of ρ c = 2.5 × 10 −5 cm 2 , sheet resistances of R SH = 3.9 k / , and maximum current densities of 75 mA/mm (at V GATE of 2 V). Electrical measurements from −50 to 200 • C had decreasing specific contact resistance and increasing sheet resistance, with increasing temperature. III-N amplifiers and power transistors are becoming increasingly important in commercial as well as in military applications, finding uses in everything from cellular base stations, to power converters, to satellites.1-2 The advent of new materials and fabrication capabilities enables further advances in this essential technology. Wide bandgap (WBG) SiC-and GaN-based devices have already improved power electronics, reducing their size and weight, compared to Si-based technologies.2 Further, increasing the Al fraction for both the channel and barrier in AlGaN high electron mobility transistors (HEMTs) has the potential to enable the production of HEMTs with higher breakdown voltages and a more attractive tradeoff between breakdown voltage and specific on-resistance, 3 thereby offering improved figures of merit. The ultra-wide-bandgap (UWBG) of AlGaN, in contrast to the WBG of GaN, also empowers devices to have enhanced temperature stability 2 and higher power density. 4 However, the advantages of higher aluminum content come with a challenge. ohmic contacts to high Al-fraction AlGaN devices are difficult to make with low contact resistance. This can be particularly challenging for contacts to HEMT structures where the 2D electron gas is contacted under a barrier layer of very high Al content AlGaN.Previous approaches to producing ohmic contacts on AlGaN HEMTs include Si ion implant under the contacts, 5,6 recessed etching 7 and selective area re-growth under ohmic contacts, 3 or planar contacts using various metallization schemes. 4,[8][9][10][11][12][13][14] Of all of these approaches, the planar, non-implanted contacts are the simplest to fabricate. A literature summary [4][5][6][14][15][16] of AlGaN HEMT contact metallurgy and the Al-fraction of the barrier and channel layers is listed in Table I. The specific contact resistance is plotted against the Al-fraction of both the barrier (Fig. 1A) and channel layers ( Figure 1B). Regardless of contact scheme, the specific contact resistance values for HEMT devices generally adhere to exponentially increasing trend l...

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Comparison of characteristics of AlGaN channel HEMTs formed on SiC and sapphire substrates

Cited by 19 publications

References 5 publications

Enhancement of two‐dimensional electron gases in AlGaN‐channel high‐electron‐mobility transistors with AlN barrier layers

Enhancement of two‐dimensional electron gases in AlGaN‐channel high‐electron‐mobility transistors with AlN barrier layers

AlGaN channel MIS-HEMTs with a very high breakdown electric field and excellent high-temperature performance

Planar Ohmic Contacts to Al_0.45Ga_0.55N/Al_0.3Ga_0.7N High Electron Mobility Transistors

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Comparison of characteristics of AlGaN channel HEMTs formed on SiC and sapphire substrates

Cited by 19 publications

References 5 publications

Enhancement of two‐dimensional electron gases in AlGaN‐channel high‐electron‐mobility transistors with AlN barrier layers

Enhancement of two‐dimensional electron gases in AlGaN‐channel high‐electron‐mobility transistors with AlN barrier layers

AlGaN channel MIS-HEMTs with a very high breakdown electric field and excellent high-temperature performance

Planar Ohmic Contacts to Al0.45Ga0.55N/Al0.3Ga0.7N High Electron Mobility Transistors

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Planar Ohmic Contacts to Al_0.45Ga_0.55N/Al_0.3Ga_0.7N High Electron Mobility Transistors