Correlation between Optical Properties and Crystallite Size in Porous Silicon

Abstract

Recently a quantum size effect was proposed to be responsible for the blue shift of optical absorption edge and photoluminescence peak wavelength as well as for the porous silicon (PS) formation itself. In the debate about the mechanism of light emission from PS a correlation between particle size and luminescence peak position would be a key test of the confinement approach. In this letter X-ray diffraction results of as-etched PS samples will be presented that indicate a decrease of particle size and an increase of stress in conjunction with a blueshift of photoluminescence wavelength and absorption edge.

Estimation of Silicon Nanocrystalline Sizes from Photoluminescence Measurements of RF Co-Sputtered Si/SiO2 Films.

“…Nevertheless, it is generally accepted that the PL emission is a consequence of a widening in the band gap due to quantum confinement in the nanocrystals [5]. Several studies confirm the presence of nanocrystals (called "quantum dots", QD) or aggregates of nanocrystals in long structures ("quantum wires", QW) in luminescent specimens [6][7][8][9][10][11][12]. The evidence points at the existence of statistical distributions of nanocrystal sizes mainly because the process of production of the specimens is highly stochastic [13][14][15][16][17].…”

Effect of microwave radiation on conductivity of porous silicon nanostructures

“…Estimated thickness of the basic layer was about six times the thickness of the auxiliary layer. Calculations of geometry and porosity of the layers were based on data depending on density of the dc current and duration of etching [14,15]. Contacts were made by vacuum evaporation of aluminium and subsequent annealing at temperature of 450 • C in nitrogen atmosphere.…”

Scaling effects upon fractal etch pattern formation on silicon photoelectrodes

“…Direct evidence for stress induced silicon wafer bending during voltage oscillations of the Si/HF system was presented by Lehman [22]. Finally, investigations with Highresolution X-ray diffraction proved the existence of stress forces across porous silicon layers [23]. The finding has been attributed to the specific termination of the pore walls by Si-H x leading predominantly to vertical strain [24,25].…”