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Extreme electronic bandgap modification in laser-crystallized silicon optical fibres

Noel Healy1, Sakellaris Mailis1, Nadezhda M.Bulgakova2,3, Pier J.A.Sazio1, Todd D.Day4,
Justin R.Sparks4, Hiu Y.Cheng4, John V.Badding4 and Anna C.Peacock1

1. Optoelectronics Research Centre, University of Southampton, UK
2. Institute of Thermophysics, SB RAS, Novosibirsk 630090, Russia
3. HiLASE, Institute of Physics ASCR, 18221 Prague, Czech Republic, 4 Department of Chemistry and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA

Abstract

For decades now, silicon has been the workhorse of the microelectronics revolution and a key enabler of the Information age. Owing to its excellent optical properties in the near- and mid-infrared, silicon is now promising to have a similar impact on photonics. The ability to incorporate both optical and electronic functionality in a single material offers the tantalizing prospect of amplifying, modulating and detecting light within a monolithic platform. However, a direct consequence of silicon's transparency is that it cannot be used to detect light at telecommunications wavelengths. Here, we report on a laser processing technique developed for our silicon fibre technology through which we can modify the electronic band structure of the semiconductor material as it is crystallized. The unique fibre geometry in which the silicon core is confined within a silica cladding allows large anisotropic stresses to be set into the crystalline material so that the size of the bandgap can be engineered. We demonstrate extreme bandgap reductions from 1.11 eV down to 0.59 eV, enabling optical detection out to 2,100nm.


Nature Materials (2014) Vol.13(12) pp.1122-1127

doi: 10.1038/NMAT4098

Southampton ePrint id: 372182

 

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