Luminescence Bands and their Proposed Origins In Highly Porous Silicon

Abstract

The striking photoluminescent properties of porous silicon nanostructures have received intense study since 1990. This literature review focuses on the large number of models proposed to account for efficient light emission. Two distinct luminescence bands in the visible spectral range have received most study. Strong evidence now exists that quantum confined carriers in crystalline Si can yield efficient red to green ('S band') luminescence. The blue ('F band') emission reported to date in oxidised porous Si is, however, unlikely to arise from quantum confinement effects.

The origin of photoluminescence from thin films of silicon-rich silica

“…[12][13][14][15][16][17][18] However, there is considerable uncertainty about the nature of the luminescence mechanism from silicon-rich silica. A number of possibilities present themselves: radiative recombination of confined excitons within silicon clusters ͑''quantum dots''͒, 23 defect luminescence, 24 interfacial effects at cluster surfaces, 25 and luminescence from novel siloxene molecules. 26 Each of these proposed mechanisms has its proponents and supporting experimental evidence, leading to a very confused picture.…”

Nanoporous silicon tubes: the role of geometry in nanostructure formation and application to light emitting diodes

“…The F band luminescence, usually centered between 420 and 500 nm, decays on the nanosecond time scale. This can be observed on porous silicon samples aged in air or intentionally oxidized, and is thought to originate from structural defects in the silicon nanocrystal oxide shell, or from the luminescence of very small silicon nanocrystals [19,39,[69][70][71][72]. Other PL bands have been previously reported for porous silicon: the so-called UV band (centered around 350 nm), and the R band (ranging from 1100-1500 nm) [59].…”

“…These porous structures contain silicon nanocrystals, which show efficient photoluminescence and electroluminescence, enabling optoelectronic and sensing applications [29][30][31][32][33][34][35][36][37]. To the best of our knowledge, all examples of the solid state electroluminescent silicon devices presented so far are based on planar geometry [10,33,[38][39][40][41].…”

Geometry Induced Localization of Electrons in Quantum Pillars

“…All of them have interesting optical properties with potential device applications [1], [3]. The Si pillars, in particular, exhibit visible luminescence at 620 rim, which is very similar to the one observed in porous Si, thus enhancing the view that this phenomenon is a quantum size effect and is not related to some surface defect or impurity complex [3], [4]. *Corresponding author.…”