Nonlinear absorption of Sb-based phase change materials due to the weakening of the resonant bond

Liu, Shuang; Wei, Jingsong; Gan, Fuxi

doi:10.1063/1.3693156

Cited by 27 publications

(20 citation statements)

References 25 publications

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“…Sb 2 Te 3 with a thickness of approximately 20 nm is subsequently deposited on the dielectric layer through a direct-current magnetron-controlling sputtering method. Sb 2 Te 3 is used as the nonlinear layer because the resonant bonding weakening induced giant nonlinear saturation absorption characteristics [12,13]. A 20 nm-thick SiN is used as the near-field layer between Sb 2 Te 3 and the recording layer.…”

Section: Experimental Results Of the Nano-optical Data Recording And mentioning

confidence: 99%

“…The w 0 (∼0.61 /NA) is approximately 380 nm. The nonlinear absorption coefficient and thickness of Sb 2 Te 3 thin film are approximately β = −2.5 × 10 −2 m/W for the laser pulse of 80 ns [13] and L = 20 nm, respectively. Figure 8.14b displays the theoretically calculated results.…”

Section: Theoretical Basis Of Super-resolution Spot Formationmentioning

confidence: 99%

“…By the thermo-physical properties dα/dT = −7.37 × 10 3 /(m · K), α 0 = 7.78 × 10 5 /cm, ρ = 6.50 × 10 3 Kg/m 3 , C p = 205.5 J/(Kg · K) [13], and the laser irradiation time t w = 80 ns, one can obtain the optical spot intensity profile according to formula (8.15). Figure 8.15a shows the comparison of the superresolution spot with the initial focused spot of the testing system where the readout laser power is set as P r = 0.9 mW.…”

Section: Theoretical Basis Of Super-resolution Spot Formationmentioning

confidence: 99%

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Applications of Nonlinear Super-Resolution Thin Films in Nano-optical Data Storage

Wei

2014

Springer Series in Optical Sciences

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Optical storage is very useful for high-definition digital television, data distribution, and memory. With the development of information technology, the capacity of optical storage devices is required to become larger and larger. Correspondingly, the density is also required to become higher and higher. In order to improve the density, one has to reduce the information bit size. The size is determined by the optical diffraction limit. That is, D ∼ 1.22 /NA, where D is the size of the focused spot, laser wavelength in vacuum, and NA the numerical aperture of optical pickup. In order to improve the capacity and density of optical storage devices, one has to shorten the laser wavelength and increase the numerical aperture of optical pickup. However, a larger NA will reduce the focal depth of pickup and increase comatic aberration when the disk tilts against the optical axis. So far, for farfield optical storage, the NA of pickup has been very close to the theoretical limit (NA = 1). To reduce the mark size, a short wavelength laser source must be used. The laser wavelength has been decreased from 780 nm for compact discs to 405 nm for blue ray disks. Further shortening the laser wavelength is difficult due to the high product cost and low transmission of general optical elements at wavelength below 360 nm.In this regard, the near-field optical probe is a very good method to generate small spot due to avoidance of the diffraction limit, and it can also record nanometric information marks. However, the low optical transmission and some problems in controlling the near-field distance between the probe tip and the sample surface meet difficulties in application to the high-speed rotation optical disk system. The solid immersion lens near-field method can obtain a subwavelength spot and produce nanometric information marks. It can also maintain a higher optical

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Section: Experimental Results Of the Nano-optical Data Recording And mentioning

confidence: 99%

Section: Theoretical Basis Of Super-resolution Spot Formationmentioning

confidence: 99%

Section: Theoretical Basis Of Super-resolution Spot Formationmentioning

confidence: 99%

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Applications of Nonlinear Super-Resolution Thin Films in Nano-optical Data Storage

Wei

2014

Springer Series in Optical Sciences

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“…Antimony telluride (Sb 2 Te 3 ) and other lead-based phase OPCMs are extensively applied in optical data storage [105,106], photo-lithography [107,108], holography [109], and topological photonics [110]. All these applications depend on the response of the material to the applied electromagnetic field, the temperature or the interaction between material and laser pulses [111].…”

Section: Antimony Telluridementioning

confidence: 99%

“…The crystalline Sb 2 Te 3 films used for core-cladding structures and mask layers exhibit a temperature-dependent transmittance, a giant optical nonlinear absorption and refraction under low laser intensity [112], due to saturation of direct bandgap transition and thermal effect, respectively [111]. The optical non-linearity and the dramatic changes in the optical properties with the phase and the film thickness indicate that the Sb 2 Te 3 and more in general Sb-based materials are promising candidates for both volatile and non-volatile photonic memristive devices.…”

Section: Antimony Telluridementioning

confidence: 99%

Perspective on photonic memristive neuromorphic computing

et al. 2020

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Neuromorphic computing applies concepts extracted from neuroscience to develop devices shaped like neural systems and achieve brain-like capacity and efficiency. In this way, neuromorphic machines, able to learn from the surrounding environment to deduce abstract concepts and to make decisions, promise to start a technological revolution transforming our society and our life. Current electronic implementations of neuromorphic architectures are still far from competing with their biological counterparts in terms of real-time information-processing capabilities, packing density and energy efficiency. A solution to this impasse is represented by the application of photonic principles to the neuromorphic domain creating in this way the field of neuromorphic photonics. This new field combines the advantages of photonics and neuromorphic architectures to build systems with high efficiency, high interconnectivity and high information density, and paves the way to ultrafast, power efficient and low cost and complex signal processing. In this Perspective, we review the rapid development of the neuromorphic computing field both in the electronic and in the photonic domain focusing on the role and the applications of memristors. We discuss the need and the possibility to conceive a photonic memristor and we offer a positive outlook on the challenges and opportunities for the ambitious goal of realising the next generation of full-optical neuromorphic hardware.

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2D or Not 2D: Strain Tuning in Weakly Coupled Heterostructures

Wang

Lange

Cecchi

et al. 2018

Adv Funct Materials

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A route to realize strain engineering in weakly bonded heterostructures is presented. Such heterostructures, consisting of layered materials with a pronounced bond hierarchy of strong and weak bonds within and across their building blocks respectively, are anticipated to grow decoupled from each other. Hence, they are expected to be unsuitable for strain engineering as utilized for conventional materials which are strongly bonded isotropically. Here, it is shown for the first time that superlattices of layered chalcogenides (Sb 2 Te 3 / GeTe) behave neither as fully decoupled two-dimensional (2D) materials nor as covalently bonded three-dimensional (3D) materials. Instead, they form a novel class of 3D solids with an unparalleled atomic arrangement, featuring a distribution of lattice constants, which is tunable. A map to identify further material combinations with similar characteristic is given. It opens the way for the design of a novel class of artificial solids with unexplored properties.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201705901.dichalcogenides (e.g., MoSe 2 , WSe 2 , TiTe 2 , etc.), and quintuple layered V 2 -VI 3 chalcogenides (e.g., Sb 2 Te 3 , Bi 2 Te 3 , and Bi 2 Se 3 ). Even septuple, nontuple, and more complex layered systems can be created when alloying the latter class of materials with IV-VI chalcogenides like GeTe, SnTe, or PbTe.The weak interlayer interaction-which causes the 2D nature of these materials-is both a blessing and a curse. On the one hand, it allows the growth of heterostructures and superlattices of dissimilar 2D materials without epitaxial guidance (vdW epitaxy). [7] Yet, it also creates adverse side effects such as poor adhesion [7] and wetting. [8] More importantly, the weak coupling impedes strain engineering. [9][10][11][12] Clearly, in the limit of zero coupling across vdW gaps, it should be impossible to introduce any strain in the growing 2D film. Yet, if enough coupling prevails across these gaps, strain engineering should be possible, too. The engineering of strain is an elegant concept to tailor physical properties without changing composition. Heteroepitaxial growth provides a versatile platform to create such strained films on appropriately chosen substrates. A manifold of novel devices have been realized by strain control, such as MOSFET transistors with strained Si, leading to 80-120% gains in electron mobility, [13,14] or quantum cascade lasers, where the growth of thicker defect-free quantum wells shortens the operation wavelengths. [15] Hence, strain engineering is also subject of numerous publications dealing with 2D systems. [16][17][18][19][20][21][22] It requires an understanding and possibly tailoring of the coupling across vdW gaps. With this goal in mind, we have investigated GeTe/Sb 2 Te 3 superlattices (SLs). These layered systems are currently attracting significant scientific interest for next-generation data storage media based on phase-change materials (interfacial pha...

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Nonlinear absorption of Sb-based phase change materials due to the weakening of the resonant bond

Cited by 27 publications

References 25 publications

Applications of Nonlinear Super-Resolution Thin Films in Nano-optical Data Storage

Applications of Nonlinear Super-Resolution Thin Films in Nano-optical Data Storage

Perspective on photonic memristive neuromorphic computing

2D or Not 2D: Strain Tuning in Weakly Coupled Heterostructures

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