Kr and Xe irradiations in lanthanum (La) doped ceria: Study at the high dose regime

Yun, Di; Oaks, Aaron; Chen, Wei‐Ying; Kirk, Marquis A.; Rest, J.; Insopov, Zinetula Z.; Yacout, Abdellatif M.; Stubbins, James F.

doi:10.1016/j.jnucmat.2011.08.005

Cited by 19 publications

(5 citation statements)

References 18 publications

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“…Recently Razdan and Shoesmith studied the trivalent dopant influence on the UO 2 structure and a strong Raman band at 540 cm −1 was attributed to the O vacancies in SIMFUEL, Gd‐doped UO 2 , and Dy‐doped UO 2 samples. This feature was previously shown by similar studies performed on cerium dioxide, which has the same crystal structure and many similar material properties as uranium dioxide and is therefore used as a good surrogate material for uranium dioxide in literature . For example, McBride et al .…”

Section: Resultsmentioning

confidence: 55%

Raman and X‐ray Studies of Uranium–Lanthanum‐Mixed Oxides Before and After Air Oxidation

et al. 2015

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UO 2 samples doped with 6, 11, 22 mol% lanthanum were examined before and after air oxidation. To verify the formation of uranium-lanthanum-mixed oxide solid solutions, powder X-ray diffraction (XRD) analyses of the crystalline phases in the materials were carried out. The presence of oxygen vacancies in the La-doped UO 2 samples was identified by Raman spectrometry. It was evidenced by changes induced in the Raman spectra by air oxidation. This latter was carried out either by increasing the Raman laser power or by thermally treating the samples at 500 K for 370 h. In addition, oxidation behavior differences of pure and La-doped UO 2 samples were reported by comparing XRD and Raman results of the samples before and after air oxidation. It was shown that the concentration of the M 4 O 9 (M: U, La) phase increased with increasing content of La, whereas inhibition for the formation of M 3 O 8 phase was observed.

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Section: Resultsmentioning

confidence: 55%

Raman and X‐ray Studies of Uranium–Lanthanum‐Mixed Oxides Before and After Air Oxidation

et al. 2015

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“…La doping in CeO 2 is expected to increase the oxygen vacancies and also 'pin' them, restraining the vacancies from migrating. 74 Gillis et al 75 reported that La atoms doped in CeO 2 tend to migrate to the surface. Taken together, these findings suggest that La doping will increase the oxygen vacancies at the surface and those vacancies would not migrate, thus permanently changing the surface state.…”

Section: Characteristics Of Ceria Abrasivesmentioning

confidence: 99%

Shallow Trench Isolation Chemical Mechanical Planarization: A Review

Ramanathan

Dandu

Babu

2015

ECS J. Solid State Sci. Technol.

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Electrical isolation of the billion or so active components in each integrated device is achieved using shallow trench isolation (STI) which requires chemical mechanical planarization (CMP) involving silicon dioxide removal at a high rate and stopping on an underlying silicon nitride film. Several colloidal slurries with various additives can yield the desired high rate selectivity between the oxide and nitride films during CMP while maintaining an acceptably low nitride rate. Here, many of such high selectivity STI CMP slurries described in the literature are reviewed along with the characteristics of the colloidal dispersions like the abrasives, additives, the interactions between them and with the films being planarized and the associated pH range in which the high selectivity is observed. The mechanisms proposed to explain the high reactivity of ceria with oxide, the role of additives in suppressing the nitride removal rate and resulting high selectivity are discussed. Reduction of a multitude of defects in post-CMP processed STI structures still remains an important challenge, especially as the feature sizes continue to shrink. Chemical mechanical planarization (CMP) is one of the important enabling processes in facilitating multilevel metallization (in some cases reaching up to 14 levels) and incorporation of novel gate and channel materials at the component level in modern semiconductor device manufacturing where its use has become widespread and ubiquitous.1-6 Here, we review recent advances and remaining challenges in one specific application of CMP, the shallow trench isolation (STI) process. STI is a method of electrically isolating active areas using trenches created in the Si substrate around the active elements and filling it with an insulating dielectric, such as silicon dioxide or silicon oxy-nitride or silicon carbonitride.7-11 Process details of the STI structures are available in numerous publications. There are a multitude of techniques available for oxide deposition and even though the resulting oxides have very different properties, for simplicity we do not distinguish between them in this review. For completeness and ease of reference, a schematic representation of the STI process is given in Figure 1. While the trenches are being filled, silicon dioxide also deposits over unwanted areas on the entire wafer (since selective deposition in trenches only is not possible) creating an uneven topography. The excess and unwanted oxide has to be completely removed and CMP has proven to be the only viable and robust global and local planarization capable process technology.Here, as shown in Figure 1, presence of a very thin silicon nitride stop layer (deposited on another thin pad oxide layer to control film stress) is an essential and integral part of the process. This nitride stop layer prevents any damage during planarization to the all-important epitaxially grown surface underneath and is itself removed by a wet etch process subsequent to the overburden oxide removal. Since the integrity of the...

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“…Lanthanum cerium oxide (La x Ce 1−x O z ) is suggested as a potential high-k reactive oxide on 4H-SiC substrate with a k value of 11.89 [14], sensitive toward oxygen gas. It differs from the previous applications as thermal barrier coating material [15]- [17], three-way automotive catalyst [18], surrogate material for uranium oxide [19], [20], and buffer layer in the development of coated Ni-W conductor [21], but not as the reactive oxide on MOS-based gas sensors. Presence of high amount of oxygen vacancies in the La x Ce 1−x O z suggests sensitivity of the oxide toward oxygen gas, which is nowadays required in the automotive industries aiming to reduce exhaust emissions in vehicles by generating a voltage signal proportional to the amount of oxygen in the exhaust.…”

Section: Introductionmentioning

confidence: 80%

Ultralow Voltage Operation of ${\rm Al}/{\rm La}_{x}{\rm Ce}_{1-x}{\rm O}_{z}/{\rm 4H\hbox{-}SiC}$ for Oxygen Sensing

Lim¹,

Cheong²

2013

IEEE Electron Device Lett.

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A metal-reactive oxide-silicon carbide (SiC) sensor, responding to oxygen gas, was fabricated using a La x Ce 1−x O z layer deposited between 4H-SiC substrate and Al gate as a function of postdeposition annealing (PDA) of the oxide layer from 400 to 1000°C. Sensitivity of the sensor increased with increasing of the PDA temperature. Current-time and currentgate voltage response was investigated in ultralow voltage regime under a forward bias of 0.3 V to study sensitivity of the sensor. Sensing mechanism of the sensor toward the oxygen gas was proposed and discussed.Index Terms-Lanthanum cerium oxide, metal reactive oxide, oxygen, silicon carbide (SiC), ultralow voltage.

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Kr and Xe irradiations in lanthanum (La) doped ceria: Study at the high dose regime

Cited by 19 publications

References 18 publications

Raman and X‐ray Studies of Uranium–Lanthanum‐Mixed Oxides Before and After Air Oxidation

Raman and X‐ray Studies of Uranium–Lanthanum‐Mixed Oxides Before and After Air Oxidation

Shallow Trench Isolation Chemical Mechanical Planarization: A Review

Ultralow Voltage Operation of ${\rm Al}/{\rm La}_{x}{\rm Ce}_{1-x}{\rm O}_{z}/{\rm 4H\hbox{-}SiC}$ for Oxygen Sensing

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