Low-resistant and high-transparent Ru/Ni ohmic contact on <i>p</i>-type GaN

Jang, Ho Won; Urbanek, W.; Yoo, M. C.; Lee, Jong‐Lam

doi:10.1063/1.1474609

Cited by 33 publications

(11 citation statements)

References 9 publications

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“…Jang and co‐workers also observed that the surface of their contacts based on Pt/Ru and Ru/Ni schemes remained smooth after annealing at 600 °C for 30 min, which is attributed to the thermodynamic stability of Ru. Parameters of these metal contacts on p‐GaN are listed in Table 1 .…”

Section: Metal Contactsmentioning

confidence: 99%

“…Following this consideration, another metal with good quality oxides, Ru, was investigated as a contact material on p‐GaN, since its metallic‐conducting oxide RuO 2 , with the rutile structure, has a large work function, low resistivity and excellent thermal stability. Jang et al used Ru intermediate layers on p‐GaN in their Ru/Ni and Pt/Ru contacts . They obtained a transparency of 84.6% at 460 nm (Ni/Ru) and 87.3% at 470 nm (Pt/Ru), respectively.…”

Section: High Transparency Materialsmentioning

confidence: 99%

“…They obtained a transparency of 84.6% at 460 nm (Ni/Ru) and 87.3% at 470 nm (Pt/Ru), respectively. The RuO 2 formed on p‐type GaN played a role in reducing the effective Schottky barrier height (SBH), since RuO 2 has a work function 1.2 eV higher than that of Ru, and a NiO layer produced on the RuO 2 acted as a diffusion barrier against out‐diffusion of the Ga and N atoms released. Formation of Pt‐Ga alloys and total removal of oxides at the contact/p‐GaN interface were observed in the Pt/Ru contact annealed in N 2 atmosphere .…”

Section: High Transparency Materialsmentioning

confidence: 99%

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Ohmic Contacts on p‐GaN

Chen

Brewer

2015

Adv Elect Materials

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With the development of GaN-based optoelectronic devices, the need for p-GaN contacts with low resistivity, good thermal stability, and high transparency or refl ectivity has become more pressing. Various contact schemes to satisfy these requirements have been investigated in the past two decades. In this progress report, the main developments of contacts on p-GaN throughout these years are summarized. The primary focus is on the materials aspects of the contacts and the functional mechanisms related to their relevant properties.

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Section: Metal Contactsmentioning

confidence: 99%

Section: High Transparency Materialsmentioning

confidence: 99%

Section: High Transparency Materialsmentioning

confidence: 99%

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Ohmic Contacts on p‐GaN

Chen

Brewer

2015

Adv Elect Materials

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“…2 The ideal metal contact to p-GaN would have a work function greater than that of GaN (;6.5 eV to 7.5 eV). 3,4 For light emitting diodes (LEDs), extraction of the light from the device is paramount to device efficiency and several contact schemes using semitransparent contacts, including oxidized Ni/Au, [5][6][7][8][9][10][11][12] Ru/Ni, 13 Pd/Ni, 14 NiAu, and Al or Ag, 15 indium-tin-oxide-based, 16 and ZnObased, 17 have been reported. The most detailed studies have been reported on the oxidized thin Ni/Au system.…”

Section: Introductionmentioning

confidence: 99%

Calculations and measurements of contact resistance of semi-transparent Ni/Pd contacts to p-GaN

Bogart

Crofton

2006

J. Electron. Mater.

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Calculations of specific contact resistance as a function of doping and barrier height were performed for p-type GaN. These calculations took into account two valence bands, each with different effective masses, and show that at low doping, the heavy hole band accounts for most of the conduction, whereas at heavier doping, the light hole band dominates conduction. These calculations also indicate the barrier height for typical contacts to p-GaN is between 0.75 eV and 1 eV. Specific contact resistance measurements were made for oxidized Ni/Au, Pd, and oxidized Ni/Pd ohmic contact metal schemes to p-GaN. The Ni/Pd contact had the lowest specific contact resistance, 6 3 10 ÿ4 V cm 2 . Auger sputter depth profile analysis showed some Ni diffused away from the GaN surface to the contact surface with the bulk of the Pd located in between two areas of Ni. Both Ni and Pd interdiffused with the GaN at the semiconductor surface. The majority of the oxygen observed was with the Ni as NiO. Angle-resolved-x-ray photoelectron spectroscopy (AR-XPS) analyses showed the formation of predominantly NiO and PdO species, with higher Ni and Pd oxides at the contact surface.

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“…Annealing in the range of 400-750 o C with these leads to typical contact resistances in the 10 -2 ~ 10 -3 Ω.cm 2 range. This anneal serves to increase the hole concentration of the p-GaN by removing hydrogen, which acts as a compensator to the Mg dopant, from the semiconductor [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The anneal also can promote the formation of low resistance interfacial phases.…”

mentioning

confidence: 99%

High temperature Ohmic contacts to p‐type GaN for use in light emitting applications

Voss

Stafford

Hlad

et al. 2008

Phys. Status Solidi (c)

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Achieving low resistance contacts to p‐type Gallium Nitride is a critical requirement for the fabrication of reliable AlGaN/InGaN laser diodes and nitride‐based light‐emitting diodes (LEDs). Three separate groups of materials are examined. The first is a family of borides, including W2B, W2B5, CrB2, TiB2, and ZrB2; the second is a group of nitrides, TaN, TiN, and ZrN; and the third is the refractory metal Ir. Using these materials both directly on the surface of p‐GaN as well as a diffusion barrier for Ni/Au‐based Ohmic contacts, specific contact resistances as low as ∼1x10–4 Ω.cm2 have been achieved. In addition, the boride and iridium based contacts display superior aging characteristics with minimal degradation of the contact resistance and of the turn on voltage of light emitting diodes after extended periods at 350 °C. The reasons for the discrepancies in performance of different materials is examined through the use of IV curves as well as Auger Electron Spectroscopy (AES) depth profiles. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Low-resistant and high-transparent Ru/Ni ohmic contact on p-type GaN

Cited by 33 publications

References 9 publications

Ohmic Contacts on p‐GaN

Ohmic Contacts on p‐GaN

Calculations and measurements of contact resistance of semi-transparent Ni/Pd contacts to p-GaN

High temperature Ohmic contacts to p‐type GaN for use in light emitting applications

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