Vanadium-based Ohmic contacts to n-AlGaN in the entire alloy composition

France, Ryan M.; Xu, Tao; Chen, Papo; Chandrasekaran, Ramya; Moustakas, T. D.

doi:10.1063/1.2458399

Cited by 98 publications

(70 citation statements)

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“…Additional details of sample growth and preparation have been published elsewhere [7]. The Au/V/Al/V contact scheme (where Au is the topmost layer) consisted of Au(100 nm)/V(20 nm)/Al(80 nm)/V(15 nm) (all thicknesses given are nominal values).…”

Section: Methodsmentioning

confidence: 99%

“…However, it was found that, with increasing Al content in the alloy, the optimal RTA temperature had to be increased for optimal specific contact resistivity [7]. Second, the employed contact schemes are very complex and empirically derived.…”

Section: Introductionmentioning

confidence: 99%

“…In the present case, a similar experimental argument cannot be applied, since the Al signal is vastly dominated by the Al atoms in the AlN substrate, and because Al is additionally present in the (initial) contact scheme. France et al found that for optimal contact resistivity in the (Al,Ga)N alloy system, the required RTA processing temperature increases with increasing Al content -varying from 650°C (pure n-GaN) to 1000°C (pure n-AlN) [7]. It was hypothesized that the RTA temperature was related to the bond strength (Eb) of Ga-N and Al-N [7].…”

mentioning

confidence: 99%

“…France et al found that for optimal contact resistivity in the (Al,Ga)N alloy system, the required RTA processing temperature increases with increasing Al content -varying from 650°C (pure n-GaN) to 1000°C (pure n-AlN) [7]. It was hypothesized that the RTA temperature was related to the bond strength (Eb) of Ga-N and Al-N [7]. Indeed, Talwar et al report that Eb,Al-N > Eb,Ga-N [24].…”

mentioning

confidence: 99%

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Chemical structure of vanadium-based contact formation on n-AlN

Pookpanratana¹,

Blum²,

Bell³

et al. 2010

Journal of Applied Physics

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Abstract:We have investigated the chemical interaction between a Au/V/Al/V layer structure and n-type AlN epilayers using soft x-ray photoemission, x-ray emission spectroscopy, and atomic force microscopy. To understand the complex processes involved in this multi-component system, we have studied the interface before and after a rapid thermal annealing step. We find the formation of a number of chemical phases at the interface, including VN, metallic vanadium, aluminum oxide, and metallic gold. An interaction mechanism for metal contact formation on the entire n-(Al,Ga)N system is proposed.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Chemical structure of vanadium-based contact formation on n-AlN

Pookpanratana¹,

Blum²,

Bell³

et al. 2010

Journal of Applied Physics

Self Cite

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“…The carrier concentration, resistivity, and mobility are determined by: Typically, metal contacts are deposited onto diced test pieces from the wafer to measure the Hall effect in semiconductors, a process that destroys the sample for other measurements and is time consuming. It also becomes increasingly more difficult to obtain ohmic contacts on AlGaN layers with increasing Al contents [125]. Contactless measurements not only solve many of the described problems but also allow fast process feedback.…”

Section: Transport Measurementsmentioning

confidence: 99%

Doping of high-Al-content AlGaN grown by MOCVD

Nilsson¹

2014

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The high-Al-content Al x Ga 1-x N, x > 0.70, is the principal wide-band-gap alloy system to enable the development of light-emitting diodes operating at the short wavelengths in the deep-ultraviolet, λ < 280 nm. The development of the deep-ultraviolet light-emitting diodes (DUV LEDs) is driven by the social and market impact expected from their implementation in portable units for water/surface disinfection and based on the damaging effect of the deep-ultraviolet radiation on the DNA of various microorganisms. Internationally, intense research and technology developments occur in the past few years, yet, the external quantum efficiency of the DUV LEDs is typically below 1%.One of the main material issues in the development of the DUV LEDs is the achievement of n-and ptype high-Al-content Al x Ga 1-x N layers with low resistivity, which is required for the electrical pumping of the diodes. The doping process becomes significantly more complex with increasing the Al content and the electrical resistivity is as high as 10 1 -10 2 Ω . cm for n-type AlN doped by silicon, and 10 7 -10 8 Ω cm for p-type AlN doped by magnesium.The present study was therefore focused on gaining a better understanding of the constraints in the doping process of the high-Al-content Al x Ga 1-x N alloys, involving mainly silicon. For this purpose, the epitaxial growth of the high-Al-content Al x Ga 1-x N and AlN by implementing the distinct hot-wall MOCVD was developed in order to achieve layers of good structural and morphological properties, and with low content of residual impurities, particularly oxygen and carbon. Substitutional point defects O N and C N may have a profound impact on the doping by their involvement in effects of ntype carrier compensation. The process temperature was varied between 1000 and up to 1400 °C, which is a principal advantage in order to optimize the material properties of the high-Al-content Al x Ga 1-x N and AlN. The epitaxial growth of the high-Al-content Al x Ga 1-x N and AlN was largely performed on 4H-SiC substrates motivated by (i) the lattice mismatch of ~ 1% along the basal plane (the smallest among other available substrates including Si and sapphire), (ii) the good thermal conductivity of 3.7 W cm -1 K -1 , which is essential to minimize the self-heating during the operation of any light-emitting diode, and (iii) the limited access to true-bulk AlN wafers. The outcome of this study is accordingly summarized and presents our understanding for (i) the complex impact of silicon and oxygen on the n-type conductivity of Al 0.77 Ga 0.23 N, representative for the alloy composition at which a drastic reduction of the n-type conductivity of Al x Ga 1-x N is commonly reported (paper 1); (ii) the strain and morphology compliance during the intentional iv doping by silicon and magnesium, and its correlation with the resistivity of highly doped layers of Al 0.82 Ga 0.18 N alloy composition (paper2); (iii) the n-type conductivity of highly Si-doped Al 0.72 Ga 0.28 N as bound by the process temperature (p...

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Selective Nitridation Crafted a High‐Density, Carbon‐Free Heterostructure Host with Built‐In Electric Field for Enhanced Energy Density Li–S Batteries

et al. 2022

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To achieve both high gravimetric and volumetric energy densities of lithium–sulfur (Li–S) batteries, it is essential yet challenging to develop low‐porosity dense electrodes along with diminishment of the electrolyte and other lightweight inactive components. Herein, a compact TiO 2 @VN heterostructure with high true density (5.01 g cm –3 ) is proposed crafted by ingenious selective nitridation, serving as carbon‐free dual‐capable hosts for both sulfur and lithium. As a heavy S host, the interface‐engineered heterostructure integrates adsorptive TiO 2 with high conductive VN and concurrently yields a built‐in electric field for charge‐redistribution at the TiO 2 /VN interfaces with enlarged active locations for trapping‐migration‐conversion of polysulfides. Thus‐fabricated TiO 2 @VN–S composite harnessing high tap‐density favors constructing dense cathodes (≈1.7 g cm –3 ) with low porosity (<30 vol%), exhibiting dual‐boosted cathode‐level peak volumetric‐/gravimetric‐energy‐densities nearly 1700 Wh L −1 cathode /1000 Wh kg −1 cathode at sulfur loading of 4.2 mg cm −2 and prominent areal capacity (6.7 mAh cm −2 ) at 7.6 mg cm −2 with reduced electrolyte (<10 µL mg −1 sulfur ). Particular lithiophilicity of the TiO 2 @VN is demonstrated as Li host to uniformly tune Li nucleation with restrained dendrite growth, consequently bestowing the assembled full‐cell with high electrode‐level volumetric/gravimetric‐energy‐density beyond 950 Wh L −1 cathode+anode /560 Wh kg −1 cathode+anode at 3.6 mg cm −2 sulfur loading alongside limited lithium excess (≈50%).

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Vanadium-based Ohmic contacts to n-AlGaN in the entire alloy composition

Cited by 98 publications

References 10 publications

Chemical structure of vanadium-based contact formation on n-AlN

Chemical structure of vanadium-based contact formation on n-AlN

Doping of high-Al-content AlGaN grown by MOCVD

Selective Nitridation Crafted a High‐Density, Carbon‐Free Heterostructure Host with Built‐In Electric Field for Enhanced Energy Density Li–S Batteries

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