Effect of Silicon Crystal Size on Photoluminescence Appearance in Porous Silicon

Abstract

The photoluminescence (PL) study in porous silicon (PS) with decreasing Si crystallites size among the pores was reported. The PL appearance is attributed to electronic confinement in columnar-like (or dotlike) structures of porous silicon. Three different pore diameter PS samples were prepared by electrochemical etching in HF-based solutions. Changes in porous silicon and Si crystallite size were studied by observing an asymmetric broadening and shift of the optical silicon phonons in Raman scattering. Fourier transform infrared spectroscopy (FTIR) was used to study the role of siloxene or other molecular species, for example, in the luminescence mechanism. This mechanism was further studied by thermal annealing of PS at different temperatures. The PL of PS sample annealed at ≥300°C for 1 hr shows that trap electronic states appear in the energy gap of the smaller nano-crystal when Si–O–Si bonds are formed. From the observation of PL, Raman, and FTIR spectroscopy, the origin of PL in terms of intrinsic and extrinsic properties of nanocrystalline silicon was discussed.

Electroluminescent Devices Based on Junctions of Indium Doped Zinc Oxide and Porous Silicon

“…This shift goes from 650 to 600 nm. This is due to the reduction of the emitting silicon filaments size present in the PS structure [15], and the intensity decrease is the result of the oxidation process which takes place in the PSL [16]. This process reduces the filament size until the filaments lose their capacity to emit light.…”

Effects of silver and gold catalytic activities on the structural and optical properties of silicon nanowires

“…The PL peak position has a blue shift with a deviation of about 20 nm, which implies that the surface oxidation induced reduction of the nanocrystal sizes, and led to higher PL peak energies. Such a blue shift due to the presence of surface oxide have recently been observed by Kumar [31]. The surface composition of the as grown and stored samples was characterized by FT-IR spectroscopy in Fig.…”

Boron Doped Ultrananocrystalline Diamond Films on Porous Silicon: Morphological, Structural and Electrochemical Characterizations

“…It presents the silicon peak shifted to 518 cm -1 from the crystalline silicon peak, 520.5 cm -1 , which is typical of porous silicon 19 . The photoluminescence band, centered in approximately 4300 cm -1 , is also a PS feature 20 . BDUND films were grown for 3 and 4h on PS substrates.…”