Si Nanoparticles as a Model for Porous Si

Dynamics of stimulated emission in silicon nanocrystals

“…X-ray absorption studies and ab initio density functional theory calculations suggest that Si-nc in SiO 2 are coated by a 1 nm thick stressed silica shell. 19 This stressed SiO 2 could enhance the formation of oxygen-related states, like silanone bonds, 9,10,[19][20][21][22][23][24] at the interface between a Si-nc and SiO 2 or in the stressed SiO 2 shell. The energy of a silanonelike bond as a function of the SivO interatomic distances is typical of a four-level scheme, originating a significant Stokes shift between absorption and luminescence.…”

“…The energy of a silanonelike bond as a function of the SivO interatomic distances is typical of a four-level scheme, originating a significant Stokes shift between absorption and luminescence. 10,[20][21][22][23] Within this scheme, photon excitation induces a strong structural relaxation of small O-saturated nanocrystals leading to transitions involving surface localized states. 24 The broad and blueshifted gain spectrum could be understood in terms of molecularlike inhomogeneous broadening mechanisms, such as different atomic surface configurations or strain fields, acting on small interface localized atoms or small silicon inclusions efficiently pumped by Si-nc through energy transfer.…”

Hydrogen Terminated Silicon Nanopowders: Gas Phase Synthesis, Oxidation Behaviour, and Si-H Reactivity

“…The increased reactivity of the latter is due to the higher surface area and convex surface curvature of these materials, resulting in larger distances of the hydrogen atoms (e.g. surfaces solely covered with (Si) 3 Si-H units), larger numbers of more reactive (Si) 2 SiH 2 and SiSiH 3 units, as well as more strongly strained Si-Si bonds [33,49]. Such size effects were reported for a number of different materials [50] (for example nanodiamond [51,52]) and their extraordinary characteristics compared to their bulk materials (for example mechanical, optical, electron transport, and magnetic properties) find versatile application [53].…”

“…Surface Si-H groups are partially oxidised by the incorporation of oxygen atoms into the Si-Si back bonds [48,57], which was supported by theoretical investigations [49,58]. However, it remains unclear at which stage the Si-H bonds are attacked.…”

The effects of hydrogen on the electronic properties of silicon

“…In particular, H atoms are known to be responsible for the passivation of the dangling bonds in porous silicon (PSi) [1]. Several groups have studied the impact on the electronic band structure of PSi, and on its optical activity [2][3][4]. The plethora of works dealing with PSi have investigated the role of many parameters suspected to be at least partly responsible for the optical activity of PSi (the quantum confinement [5], the localized surface states [6], the amorphous nature of PSi [7], the dimension of the confinement: quantum well [8], quantum wire [3,9], and quantum dot-like models [10], the crystallite size effects [11,3,4], the oxygen effects [4], the hydrogen effects [2][3][4], etc.…”