The improvement of ohmic contact of Ti/Al/Ni/Au to AlGaN/GaN HEMT by multi-step annealing method

Feng, Qian; Li, Limei; Hao, Yue; Ni, JinYu; Zhang, Jincheng

doi:10.1016/j.sse.2009.06.002

Cited by 49 publications

(28 citation statements)

References 9 publications

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“…4 To obtain ohmic contact, a variety of novel contact schemes has been proposed by several research groups. [4][5][6][7][8][9] For p-AlGaN, thin p-GaN capping layer has been added above the p-AlGaN layer to improve the quality of the conductive layer and then the typical oxidized Ni/Au metallization scheme was employed for the p-GaN contact. 5,6 This technique can effectively meliorate the contact to the p-type conductive layer, however, it would not work for the n-type layer because normally, the n-AlGaN is embedded below the active layer.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, some groups tried to reduce the contact resistance by enhancing the donor ionization, 7 and others used Ti-and V-based alloys to lower the metal work function. 8,9 It has been reported that the formation of TiAl alloy can effectively reduce the Schottky barrier height and the introduction of nitrogen vacancies during annealing can increases the donor concentration. 8 Although many efforts has been made for obtaining lower resistance contact through Ti-based metallization, 10,11 understanding of the formation mechanism of ohmic contact remains elusive due to the complicated interface condition.…”

Section: Introductionmentioning

confidence: 99%

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Ohmic contact to n-AlGaN through bonding state transition at TiAl interface

Zhang

Wang

et al. 2012

Journal of Applied Physics

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We report the optimized ohmic contact to high Al content n-AlGaN through modification of the interfacial bonding state of TiAl alloy. First-principles calculations demonstrate that the change of interfacial bonding state (N rich to Al rich) at the TiAl/n-AlGaN interface is crucial for the formation of low barrier contact. The significant electron-transfer and strong orbital hybridization between the Ti atoms and the nearest Al atoms plays a key role in lowering the contact barrier. After treatment of the TiAl/n-AlGaN sample via rapid thermal annealing, perfectly linear I-V characteristic is achieved and the elemental profile by Auger electron spectroscopy confirms the N-rich-to-Al-rich local state transition in the interfacial layers. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4727848

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ohmic contact to n-AlGaN through bonding state transition at TiAl interface

Zhang

Wang

et al. 2012

Journal of Applied Physics

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“…For the Ti/Al/Ni/Au contact, Fan et al 127 reported an optimum annealing temperature of 750 C, and the multi-metal layer scheme has been widely used to form Ohmic contact on GaN. [128][129][130][131][132] In Schottky contacts, the degradation varies according to the metal employed. For Pd, Pt, Au, and Ni, degradation starts after exposure to temperatures as low as 300, 400, 575, and 600 C, respectively.…”

Section: B High Temperature Performancementioning

confidence: 99%

Review of using gallium nitride for ionizing radiation detection

Wang

Mulligan

Brillson

et al. 2015

Applied Physics Reviews

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With the largest band gap energy of all commercial semiconductors, GaN has found wide application in the making of optoelectronic devices. It has also been used for photodetection such as solar blind imaging as well as ultraviolet and even X-ray detection. Unsurprisingly, the appreciable advantages of GaN over Si, amorphous silicon (a-Si:H), SiC, amorphous SiC (a-SiC), and GaAs, particularly for its radiation hardness, have drawn prompt attention from the physics, astronomy, and nuclear science and engineering communities alike, where semiconductors have traditionally been used for nuclear particle detection. Several investigations have established the usefulness of GaN for alpha detection, suggesting that when properly doped or coated with neutron sensitive materials, GaN could be turned into a neutron detection device. Work in this area is still early in its development, but GaN-based devices have already been shown to detect alpha particles, ultraviolet light, X-rays, electrons, and neutrons. Furthermore, the nuclear reaction presented by 14N(n,p)14C and various other threshold reactions indicates that GaN is intrinsically sensitive to neutrons. This review summarizes the state-of-the-art development of GaN detectors for detecting directly and indirectly ionizing radiation. Particular emphasis is given to GaN's radiation hardness under high-radiation fields.

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“…and 30 s at 900°C [11,12]. Square (0.9 × 0.9) mm, 50 Å-thick Ir contacts were deposited as Schottky contacts.…”

Section: Methodsmentioning

confidence: 99%

Implementation of an AlGaN-based solar-blind UV four-quadrant detector

Schalkwyk

Meyer

Nel

et al. 2014

Physica B: Condensed Matter

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An AlGaN-based front illuminated intrinsically solar-blind ultraviolet four-quadrant Schottky detector was fabricated and characterized. A layered ohmic structure was deposited followed by a multi-step annealing method. Ultraviolet transmissive iridium oxide was used as the Schottky barrier material and formed by a two-step annealing method. Au contacts were deposited on the Schottky contacts and annealed. The detector was mounted onto a commercial chip carrier and wires were epoxy bonded from the ohmic and Au contacts to the carrier strips. The detector had an average ideality factor of 1.97 ± 0.08, a Schottky barrier height of (1.22 ± 0.07) eV, a reverse leakage current density of (2.1 ± 4) nA/cm 2 , a series resistance of (120 ± 30) Ω and a free carrier concentration of (1.6 ± 0.3) × 10 18 cm −3 . Spectral characterization on the photosensitive area of 7.3 × 10 −3 cm 2 yielded a cut-off wavelength at (275 ± 5) nm (4.59 eV to 4.23 eV) for each quadrant, corresponding to the absorption edge of a (46 ± 3)% Al content AlGaN-based material. The detector had an average responsivity of (28 ± 2) mA/W and quantum efficiency of (14 ± 1)% at 250 nm. The ultraviolet-to-visible and near-infrared rejection ratio was between 10 3 and 10 5 for most of the quadrants. Characterization showed uniformity across the quadrants, proving the detector feasible for implementation in future ultraviolet-sensitive electro-optic devices.

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The improvement of ohmic contact of Ti/Al/Ni/Au to AlGaN/GaN HEMT by multi-step annealing method

Cited by 49 publications

References 9 publications

Ohmic contact to n-AlGaN through bonding state transition at TiAl interface

Ohmic contact to n-AlGaN through bonding state transition at TiAl interface

Review of using gallium nitride for ionizing radiation detection

Implementation of an AlGaN-based solar-blind UV four-quadrant detector

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