Abstract
The effect of using different electrolytes in the physical and optical properties of porous silicon was studied. To do this porous silicon (PS) samples photoluminescent in the visible range from (100) oriented n‐type crystalline silicon prepared by anodic etching were obtained. The first electrolyte was composed of a mixture of hydrofluoric acid (HF) and ethanol (CH3‐CH2‐OH) in a ratio of 1 : 2, respectively. The second was composed of hydrofluoric acid (HF), ethanol (CH3‐CH2‐OH), and hydrogen peroxide (H2O2) in a ratio of 1 : 1 : 2, respectively. Raman scattering, photoluminescence (PL), gravimetry, scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS) measurements on the PSL were carried out. Raman scattering showed that the disorder in the samples obtained with H2O2 is greater than in the samples obtained without this. The PL from PS increased in intensity with the incremental change in the anodization time and showed a blueshift. The blueshift of PL is consistent with the reduction in size of the silicon nanocrystallites. The sizes of nanocrystals were estimated to be 3.08, 2.6, and 2.28 nm. The gravimetric analysis showed that the porosity increased with the incorporation of H2O2. SEM images (morphological analysis) showed an incremental change in the quantity and in the porous size.
Highlights
With the discovery of light emission from porous silicon (PS) made by Canham [1], the possibility of the use of silicon as an efficient light source became attractive due to the potential applications in optoelectronics [2] and electroluminescent devices [3], because this source would be compatible with the existing manufacturing infrastructure for ultra-large-scaleintegrated circuits
Where m1 is the mass of the wafer of crystalline silicon (c-Si) before the attack, m2 is the mass of the wafer after the anodization, and m3 is the mass of the same wafer after removing the porous silicon layers (PSL)
We can see that the contribution around 533 nm barely shows change and it takes importance, since it is almost equal in intensity to the emission centered at 578 nm. These results suggest that the peroxide promotes the attack in the edges of the pores and is reflected in a thinning in the silicon nanocrystals, which originates the shift to low wavelengths
Summary
With the discovery of light emission from porous silicon (PS) made by Canham [1], the possibility of the use of silicon as an efficient light source became attractive due to the potential applications in optoelectronics [2] and electroluminescent devices [3], because this source would be compatible with the existing manufacturing infrastructure for ultra-large-scaleintegrated circuits. Some works report the use of hydrogen peroxide in obtaining of luminescent samples of PS [2]. It has been proposed that the quantum confinement in crystallites [4] or wires [5] is at the origin of the luminescence in the visible range. There are many hypotheses to explain the origin of the photoluminescence Some of these theories involve siloxenes [6], polysilanes, or hydrides [7] on the surface of PS. We mean the way the etched surface of the silicon wafer is changed due to the inclusion of hydrogen peroxide in the electrolyte. PS samples were prepared by anodic etching of (100) oriented n-type c-Si and the effect of two kinds of electrolytes in obtaining porous silicon layers (PSL) was analyzed. The first electrolyte was composed of a mixture of hydrofluoric acid (HF) and ethanol (CH3-CH2-OH) in a ratio of 1 : 2, respectively, and the second was composed of HF, ethanol, and H2O2 in a ratio of 1 : 1 : 2, respectively
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