W and WSix Ohmic contacts on <i>p</i>- and <i>n</i>-type GaN

Cao, X. A.; Ren, F.; Pearton, S. J.; Zeitouny, A.; Eizenberg, M.; Zolper, J.C.; Abernathy, C. R.; Han, Joong‐Soo; Shul, R. J.; Lothian, J. R.

doi:10.1116/1.581799

Cited by 7 publications

(8 citation statements)

References 24 publications

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“…Neither other organic gaseous products nor reactive intermediates such as W(CO) n (n=1-5) were revealed for the heterogeneous thermolysis of W(CO) 6 6 Based on the obtained MS data, low temperature CVD experiments from W(CO) 6 were performed within the T d range of o C and in the presence of H 2 . VUV irradiation and addition of Pd hexafluoroacetylacetonate Pd(hfa) 2 were investigated for their potential to modify films characteristics.…”

Section: Methodsmentioning

confidence: 99%

“…Indeed, in addition to its high melting point, tungsten presents high density and low reactivity/toxicity. For these reasons W-based films find applications as ohmic contacts, diffusion barriers and interconnects in microelectronic devices [1][2][3][4]. W films on polymers may be useful for electromagnetic or radiation shielding of polymer-packaged devices [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Deposition in presence of hydrogen results in the increase of the metal content in the film. Sublimed palladium hexafluoracetylacetonate Pd(hfa) 2 was used for Pd catalytic promotion of the deposition process. Codeposition with Pd(hfa) 2 in hydrogen increases W-metal fraction and oxygen content while the Pd content is up to 10 at.%.…”

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confidence: 99%

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Thermal decomposition of tungsten hexacarbonyl: CVD of W‐containing films under Pd codeposition and VUV assistance

Krisyuk

Koretskaya

Turgambaeva

et al. 2015

Phys. Status Solidi C

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Experiments on chemical vapor deposition of W(CO)6‐derived films on silicon substrates were carried out at total pressure of 5‐10 Torr within the temperature range of 250‐350 °C; in Ar or H2 flow. Metallic, carbide and oxide phases composed the obtained films. Deposition in presence of hydrogen results in the increase of the metal content in the film. Sublimed palladium hexafluoracetylacetonate Pd(hfa)2 was used for Pd catalytic promotion of the deposition process. Codeposition with Pd(hfa)2 in hydrogen increases W‐metal fraction and oxygen content while the Pd content is up to 10 at.%. Influence of vacuum ultraviolet (VUV) radiation from Xe excimer lamp (λ ∼172 nm) on the quality of the obtained films was investigated. It was found that VUV irradiation can reduce the oxygen‐content in the film while W‐metal fraction slightly increases. In all films, oxygen was in the form of WO3 and carbon was mainly incorporated as a graphite metastable phase. The influence of other chemical additives is discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal decomposition of tungsten hexacarbonyl: CVD of W‐containing films under Pd codeposition and VUV assistance

Krisyuk

Koretskaya

Turgambaeva

et al. 2015

Phys. Status Solidi C

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“…The fundamental mechanism for p‐type conduction in GaN is the post growth high temperature annealing which activates Mg by breaking the Mg‐H complex . Polarization doping and various p‐ohmic metal stacks with a combination of work functions (Ni, Au, Ag, Pt, Pd, Au, and Re, W) have been explored for low resistance contacts . Ni/Au is the most widely used p‐ohmic contact on p‐GaN .…”

Section: Introductionmentioning

confidence: 99%

Improved Mg Dopant Activation in p-GaN and Enhanced Electroluminescence in InGaN/GaN LEDs by Plasma Immersion Ion Implantation of Phosphorus

Upadhyay

Saha

2018

Phys. Status Solidi A

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In this study, the authors demonstrate improved p‐type Mg dopant activation near surface by P ion implantation, which otherwise remain inactive due to a combination of self compensation, formation of Mg‐H complexes and high activation energy. The improvement is mainly attributed to the reduction in self‐compensation by a reduction in N vacancies near the surface and potential formation of by‐products suppressing Mg‐H complexes. In addition, inclusion of P by plasma‐immersion ion implantation creates a non‐uniform dopant activation leading to a built‐in electric field which further assists in ionizing the Mg dopants. The near‐surface improved p‐ dopant activation is manifested as a reduction in the contact resistance and specific contact resistivity. The contact resistance and specific contact resistivity are found to decrease by 68.7 and 77.4%, respectively, for P implanted p‐GaN samples in comparison to that of the control samples. The enhanced p‐doping is found to increase electro‐luminescence intensity by 264% for P implanted p‐top electrically injected light emitting diodes. The improved p‐type properties for GaN may find potential applications in the realization of electrically injected high efficiency optoelectronic devices.

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“…[4][5][6][7] Recently, W-and Cr-based ohmic contacts to n-type GaN were found to enhance the long-term thermal stability. 8,9 However, it is difficult to obtain such low contact resistivities on p-type GaN because of the low hole concentrations in p-type GaN and high Schottky barrier height at the interface of metal with p-type GaN. 3 In fact, one of the main obstacles in realizing the continuous wave operation of GaN-based laser diodes (LDs) was the high contact resistance on p-type GaN.…”

mentioning

confidence: 99%

Microstructural Investigation of Ni/Au Ohmic Contact on p-Type GaN

Kim

Lee

et al. 2000

J. Electrochem. Soc.

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Microstructural changes in Ni/Au contacts to p-type GaN as a function of annealing temperature were investigated using X-ray diffraction, field emission scanning electron microscopy, and cross-sectional transmission electron microscopy combined with energy dispersive spectroscopy. The results obtained were used to interpret the electrical properties of Ni/Au ohmic contacts to p-type GaN. The contact resistivity decreased from 1.4 ϫ 10 Ϫ2 to 6.1 ϫ 10 Ϫ4 ⍀ cm 2 after annealing at 600ЊC. The reduction in contact resistivity resulted from the dissolution of Ga atoms into the Au-Ni solid solution produced during annealing. Au atoms diffused to the GaN substrate through grain boundaries and reacted with Ni atoms at the grain boundaries of Ni, producing an Au-Ni solid solution. This resulted in the evolution of microstructure with island-shaped Ni grains surrounded by the Au-Ni solid solution. At this stage, Ga atoms outdiffused from the GaN substrate and dissolved into the Au-Ni solid solution, leading to the generation of Ga vacancies below the contact. Thus, the net concentration of holes below the contact increased, and so the contact resistivity was reduced. When the sample was annealed at 800ЊC, the Au layer completely reacted with the Ni layer, uniformly producing an Au-Ni solid solution containing Au-Ga and Ni-Ga compounds. Simultaneously, N atoms reacted with Ni, and produced cubic Ni 4 N in the vicinity of the metal/GaN interface. Consequently, N vacancies, acting as donors in GaN, were generated below the contact, leading to an increase of contact resistivity to 4.0 ϫ 10 Ϫ2 ⍀ cm 2 .

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W and WSix Ohmic contacts on p- and n-type GaN

Cited by 7 publications

References 24 publications

Thermal decomposition of tungsten hexacarbonyl: CVD of W‐containing films under Pd codeposition and VUV assistance

Thermal decomposition of tungsten hexacarbonyl: CVD of W‐containing films under Pd codeposition and VUV assistance

Improved Mg Dopant Activation in p-GaN and Enhanced Electroluminescence in InGaN/GaN LEDs by Plasma Immersion Ion Implantation of Phosphorus

Microstructural Investigation of Ni/Au Ohmic Contact on p-Type GaN

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