Crystal structure of laser-induced subsurface modifications in Si

Verburg, P.C.; Smillie, Lachlan; Römer, G.R.B.E.; Haberl, Bianca; Bradby, Jodie; Williams, James S.; Veld, A.J. Huis in ’t

doi:10.1007/s00339-015-9238-5

Cited by 31 publications

(16 citation statements)

References 41 publications

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“…Interestingly, a further study using ns-lasers (and thus equilibrium conditions) also reported the formation of R8-Si as detected by Raman microspectroscopy. 147 In this case, an IR laser was used to enable a focal point well beneath the surface of the Si. Thus, confinement appears to prevent any ablation and alters the laser-material interactions.…”

Section: B Synthesis Far Away From Equilibriummentioning

confidence: 99%

Pathways to exotic metastable silicon allotropes

Haberl

Strobel

Bradby

2016

Applied Physics Reviews

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The Group 14 element silicon possesses a complex free-energy landscape with many (local) minima, allowing for the formation of a variety of unusual structures, some of which may be stabilized at ambient conditions. Such exotic silicon allotropes represent a significant opportunity to address the ever-increasing demand for novel materials with tailored functionality since these exotic forms are expected to exhibit superlative properties including optimized band gaps for solar power conversion. The application of pressure is a well-recognized and uniquely powerful method to access exotic states of silicon since it promotes large changes to atomic bonding. Conventional high-pressure syntheses, however, lack the capability to access many of these local minima and only four forms of exotic silicon allotropes have been recovered over the last 50 years. However, more recently, significant advances in high pressure methodologies and the use of novel precursor materials have yielded at least three more recoverable exotic Si structures. This review aims to give an overview of these innovative methods of high-pressure application and precursor selection and the recent discoveries of new Si allotropes. The background context of the conventional pressure methods and multitude of predicted new phases are also provided. This review also offers a perspective for possible access to many further exotic functional allotropes not only of silicon but also of other materials, in a technologically feasible manner.

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Section: B Synthesis Far Away From Equilibriummentioning

confidence: 99%

Pathways to exotic metastable silicon allotropes

Haberl

Strobel

Bradby

2016

Applied Physics Reviews

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“…On this prospect, long pulses (nanosecond duration or more) are clearly more favorable because of reduced peak power and a thermal runaway beneficial for energy deposition. However, the level of controllability on the morphology, type, and resolution of the modifications is very limited due to the thermal nature of material transformations [8][9][10][11][12]. For increased control, the ultrafast optical breakdown regimes are thus attractive.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Laser Writing Deep inside Silicon with THz-Repetition-Rate Trains of Pulses

2020

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Three-dimensional laser writing inside silicon remains today inaccessible with the shortest infrared light pulses unless complex schemes are used to circumvent screening propagation nonlinearities. Here, we explore a new approach irradiating silicon with trains of femtosecond laser pulses at repetition rates up to 5.6 THz that is order of magnitude higher than any source used for laser processing so far. This extremely high repetition rate is faster than laser energy dissipation from microvolume inside silicon, thus enabling unique capabilities for pulse-to-pulse accumulation of free carriers generated by nonlinear ionization, as well as progressive thermal bandgap closure before any diffusion process comes into play. By space-resolved measurements of energy delivery inside silicon, we evidence changes in the interplay between detrimental nonlinearities and accumulation-based effects. This leads to a net increase on the level of space-time energy localization. The improvement is also supported by experiments demonstrating high performance for 3D laser writing inside silicon. In comparison to repeated single pulses, irradiation with trains of only four-picosecond pulses with the same total energy leads to an apparent decrease of the energy threshold for modification and drastic improvements on the repeatability, uniformity, and symmetricity of the produced features. The unique benefits of THz bursts can provide a new route to meet the challenge of 3D inscription inside narrow bandgap materials.

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“…The advent of high-power nanosecond infrared (IR) laser sources has helped to circumvent these limitations [3,4]. Advanced characterizations of the laser-modified materials with a constant focus have shed light on a wide variety of crystalline structures induced in the bulk of c-Si by these pulses, including polycrystalline phases [5], voids [6], and high-pressure phases [7]. This diversity is similar to what can be produced on the surface of silicon at wavelengths below 1.1 μm for which the material is not transparent [8][9][10].…”

mentioning

confidence: 99%