<i>In situ</i> and real-time monitoring of structure formation during non-reactive sputter deposition of lanthanum and reactive sputter deposition of lanthanum nitride

Krause, B.; Kuznetsov, Dmitry; Yakshin, Andrey; Ibrahimkutty, Shyjumon; Baumbach, Tilo; Bijkerk, F.

doi:10.1107/s1600576718007367

Cited by 15 publications

(8 citation statements)

References 39 publications

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“…The lowest possible total energy of the wurtzite structure is also 16 meV (per formula unit) lower than that of the rock-salt structure. In our phonon calculations [not shown] for the wurtzite and zinc-blende structures, both are dynamically stable at 0 K. Our theoretical results thereby support the recent experimental findings of synthesized wurtzite and zinc-blende LaN [52].…”

Section: Resultssupporting

confidence: 88%

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LaN Structural and Topological Transitions Driven by Temperature and Pressure

Chen,

Lin,

Maciejko

et al. 2021

Preprint

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We study lanthanum mononitride LaN by first-principles calculations. The commonly reported rock-salt structure of F m 3m symmetry for rare-earth monopnictides is found dynamically unstable for LaN at zero temperature. Using density functional theory and evolutionary crystal prediction, we discover a new, dynamically stable structure with P 1 symmetry at 0 K. This P 1-LaN exhibits spontaneous electric polarization. Our ab initio molecular dynamics simulations of finite-temperature phonon spectra further suggest that LaN will undergo ferroelectric and structural transitions from P 1 to F m 3m symmetry, when temperature is increased. Moreover, P 1-LaN will transform to a tetragonal structure with P 4/nmm symmetry at a critical pressure P = 18 GPa at 0 K. Electronic structures computed with an advanced hybrid functional show that the high-temperature rock-salt LaN can change from a trivial insulator to a strong topological insulator at P ∼ 14 GPa. Together, our results indicate that when P = 14 − 18 GPa, LaN can show simultaneous temperature-induced structural, ferroelectric, and topological transitions. Lanthanum monopnictides thereby provide a rich playground for exploring novel phases and phase transitions driven by temperature and pressure.

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Section: Resultssupporting

confidence: 88%

“…Indeed, a previous X-ray diffraction (XRD) experiment has reported the observation of rock-salt LaN [51]. However, a recent experiment using magnetron sputtering found only wurtzite and zinc blende structures for LaN [52]. As a result, we begin by using DFT to examine the structural stability.…”

Section: Resultsmentioning

confidence: 99%

LaN Structural and Topological Transitions Driven by Temperature and Pressure

Chen,

Lin,

Maciejko

et al. 2021

Preprint

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“…2a) of La dopants in Ta 3 N 5 has well-separated 3d 5/2 and 3d 3/2 spin-orbit components, each of which can be deconvoluted into two sets of Gaussian peaks. For the 3d 5/2 component, the peaks at 830.8 and 834.7 eV are attributed to La 3+ in the oxidation state and its satellites peak 25,26 , respectively, while the peaks at 837.3 and 840.9 eV correspond to La-N bonds 27,28 . Quantitative XPS analyses show that the La/Ta ratio in the La-doped Ta 3 N 5 thin film is 2.97%.…”

Section: Resultsmentioning

confidence: 99%

Decoupling light absorption and carrier transport via heterogeneous doping in Ta3N5 thin film photoanode

et al. 2022

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The trade-off between light absorption and carrier transport in semiconductor thin film photoelectrodes is a major limiting factor of their solar-to-hydrogen efficiency for photoelectrochemical water splitting. Herein, we develop a heterogeneous doping strategy that combines surface doping with bulk gradient doping to decouple light absorption and carrier transport in a thin film photoelectrode. Taking La and Mg doped Ta3N5 thin film photoanode as an example, enhanced light absorption is achieved by surface La doping through alleviating anisotropic optical absorption, while efficient carrier transport in the bulk is maintained by the gradient band structure induced by gradient Mg doping. Moreover, the homojunction formed between the La-doped layer and the gradient Mg-doped layer further promotes charge separation. As a result, the heterogeneously doped photoanode yields a half-cell solar-to-hydrogen conversion efficiency of 4.07%, which establishes Ta3N5 as a leading performer among visible‐light‐responsive photoanodes. The heterogeneous doping strategy could be extended to other semiconductor thin film light absorbers to break performance trade-offs by decoupling light absorption and carrier transport.

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“…A further reduction in the working wavelength to 6.7 nm and the use of beyond extreme ultraviolet (BEUV) radiation will boost the performance of microprocessors even more [5,9]. Significant efforts were directed into this direction by ASML, which is the world's largest manufacturer of DUV and EUV lithographical equipment [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Multilayer Reflective Coatings for BEUV Lithography: A Review

Uzoma

Salman

et al. 2021

Nanomaterials

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The development of microelectronics is always driven by reducing transistor size and increasing integration, from the initial micron-scale to the current few nanometers. The photolithography technique for manufacturing the transistor needs to reduce the wavelength of the optical wave, from ultraviolet to the extreme ultraviolet radiation. One approach toward decreasing the working wavelength is using lithography based on beyond extreme ultraviolet radiation (BEUV) with a wavelength around 7 nm. The BEUV lithography relies on advanced reflective optics such as periodic multilayer film X-ray mirrors (PMMs). PMMs are artificial Bragg crystals having alternate layers of “light” and “heavy” materials. The periodicity of such a structure is relatively half of the working wavelength. Because a BEUV lithographical system contains at least 10 mirrors, the optics’ reflectivity becomes a crucial point. The increasing of a single mirror’s reflectivity by 10% will increase the system’s overall throughput six-fold. In this work, the properties and development status of PMMs, particularly for BEUV lithography, were reviewed to gain a better understanding of their advantages and limitations. Emphasis was given to materials, design concepts, structure, deposition method, and optical characteristics of these coatings.

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In situ and real-time monitoring of structure formation during non-reactive sputter deposition of lanthanum and reactive sputter deposition of lanthanum nitride

Cited by 15 publications

References 39 publications

LaN Structural and Topological Transitions Driven by Temperature and Pressure

LaN Structural and Topological Transitions Driven by Temperature and Pressure

Decoupling light absorption and carrier transport via heterogeneous doping in Ta3N5 thin film photoanode

Multilayer Reflective Coatings for BEUV Lithography: A Review

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