Porous Silicon Multilayer Mirrors and Microcavity Resonators for Optoelectronic Applications

1998 ◽  
Vol 536 ◽  
Author(s):  
S. Chan ◽  
L. Tsybeskov ◽  
P.M. Fauchet
Keyword(s):  
Refractive Index ◽  
Porous Silicon ◽  
Current Density ◽  
Silicon Film ◽  
Light Output ◽  
Blue Shift ◽  
Optical Filters ◽  
Multilayer Structures ◽  
Maximum Reflectivity ◽  
The Difference

AbstractPorous silicon multilayer structures are easily manufactured using a periodic current density square pulse during the electrochemical dissolution process. The difference in porosity profile, corresponding to a variation in current density, is attributed to a difference in refractive index. Manipulating the difference in refractive index, high quality optical filters can be made with a maximum reflectivity peak ˜ 100%. The next logical step to further exploit these optical mirrors is to incorporate them into an LED device. The benefit of adding a multilayer mirror below a luminescent film of porous silicon is to significantly reduce the amount of light loss to the silicon substrate and increase the light output. However, oxidation is required to stabilize the as-anodized porous silicon film. This disrupts the overall index profile of the multilayer stack, causing the peak reflectance to blue shift. This phenomenon must be quantified and accounted before device implementation. We present a detailed study on the effects of oxidation temperature, gas environment, and annealing time of porous silicon multilayer structures in a device configuration.

The Preparation of p-PS and its Photoluminescence Properties

2013 ◽  
Vol 538 ◽  
pp. 81-84
Author(s):  
Lan Li Chen ◽  
Hai Hong Wang ◽  
Ming Ji Shi ◽  
Sheng Zhao Wang ◽  
Wen Fang Si
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Electrochemical Etching ◽  
Volume Ratio ◽  
Blue Shift ◽  
Red Shift ◽  
Luminous Intensity ◽  
Experimental Result ◽  
Anodic Current Density ◽  
Mixed Solution

In this research, p-type porous silicon was successfully fabricated with a typical electrochemical etching method. The mixed solution of HF and absolute ethyl alcohol with different volume ratio was used as the electrolyte in this experiment. The anodic current density was 20 mA/cm2～60 mA/cm2. The luminous intensity of the PS samples increased with the increasing of the current density, the peaks of PL first red shift (from 692.1nm to 727.9nm) then blue shift (from 727.9nm to719.6nm). With the increasing of the concentration of HF, PS luminous intensity gradually decreases, and the peaks of PL gradually occurs red shift. And possible mechanisms of the growth and the photoluminescence of porous silicon were proposed to explain the experimental result．

The Relationship of Porous Silicon Film Morphology to The Photoluminescence Spectra

1993 ◽  
Vol 298 ◽  
Author(s):  
John Penczek ◽  
R. L. Smith
Keyword(s):  
Porous Silicon ◽  
Silicon Film ◽  
Blue Shift ◽  
Electrochemical Process ◽  
Porous Films ◽  
Pl Spectra ◽  
Formation Conditions ◽  
Relationship Of ◽  
Silicon Dissolution ◽  
The Relationship

AbstractPhotoluminescence (PL) spectra are presented for porous silicon samples formed under various formation conditions in aqueous HF solutions. Formation conditions are chosen that effect maximal changes in morphology of resultant films and that correspond to varying formation electrochemistry. The trends in PL center wavelength and full width at half maximum (FWHM) with formation conditions are examined and compared to the resulting morphology. The PL spectra were observed to be most affected by changes in formation conditions when porous films are formed where the electrochemical process of silicon dissolution changes from a 2e- to 4e- (oxide production) reaction. Under these conditions, decreasing HF concentration and/or increasing current density produces a spectral blue-shift which is proportional to the narrowing of the FWHM. This behavior corresponds to morphology changes which are consistent with the quantum confinement model.

Optical Interference Filters Made of Porous Silicon

1996 ◽  
Vol 431 ◽  
Author(s):  
M. Thönissen ◽  
M. G. Berger ◽  
M. Krüger ◽  
S. Billat ◽  
R. Arens-Fischer ◽  
...  
Keyword(s):  
Refractive Index ◽  
Porous Silicon ◽  
Current Density ◽  
Layer Structure ◽  
Single Layer ◽  
Bragg Reflectors ◽  
Optical Interference ◽  
Interference Filters ◽  
Thickness Measurements ◽  
Reflectance Measurements

AbstractPorous silicon (PS) layers can easily be formed by an electrochemical etch process using a mixture of hydrofluoric acid (HF) and ethanol. The microstructure and porosity of the layers depend on the HF concentration, the doping level of the substrate and the current density applied during the etch process. Changing the current density during the etch process will result in a well defined layer structure consisting of layers with different porosities. Each single layer can be treated as an effective medium exhibiting a refractive index depending mainly on the porosity of the layer. Using reflectance measurements we have investigated the dependence of the refractive index of PS layers on the formation current density for different substrates. In addition the etch rate was determined by thickness measurements with an electron microscope. Based on these results various kinds of optical interference filters were studied. We have formed samples consisting of discrete single layers with different porosities (e.g. Bragg reflectors) as well as samples with continuous variation of the refractive index (rugate filters). Combining these PS filters with standard photolithography steps, microoptical devices such as spectral sensitive photodiodes can be realized.

Synthesis and Characterization of Si Nanoparticles Obtained on Sonication of Porous Silicon Multilayer Films

2012 ◽  
Vol 17 ◽  
pp. 13-25 ◽  
Author(s):  
Paresh G. Kale ◽  
Sharma Pratibha ◽  
Chetan S. Solanki
Keyword(s):  
Surface Modification ◽  
Porous Silicon ◽  
Current Density ◽  
Quantum Confinement ◽  
Blue Shift ◽  
Vis Spectroscopy ◽  
Si Nanoparticles ◽  
Confinement Behavior ◽  
Si Quantum Dots

Synthesis of Si quantum dots (QDs), useful for multi-junction crystalline Si solar cells, using porous Silicon (PS) is presented in this paper. Four types of freestanding PS structures are fabricated by anodization method with modulation of current density between two levels. The level-1 current density is kept constant at 20 mA/cm2 (for reference monolayer structure - sample A) and 10 mA/cm2 (for all multilayer structures samples B, C, D). The level-2 is varied between 0 to 50 mA/cm2 (0, 20, 30, 50 mA/cm2 as sample A, B, C and D respectively). In order to obtain Si QDs from PS films, the films are subjected to sonication (120 W, 42 kHz) for 6 hours. HRTEM images confirm presence of Si nanoparticles in the range of 2 to 8 nm. Various spectroscopic analyses of Si nanoparticles are performed in order to evaluate quantum confinement behavior and surface modification observed during sonication. Analysis of de-convoluted Raman peaks shows frequency downshift and increase in full width half maximum due to formation of QDs. After sonication, PL spectroscopy indicates blue shift from 2.54 eV (sample A) to 2.85 eV (sample D_6HR), similar to the observations made by UV-Vis spectroscopy. FTIR spectra show oxidation of Si QDs during sonication. Spectroscopic and microscopic results are explained using quantum confinement and surface modification phenomenon.

Electrical and Optical Behavior of Al2O3/Porous Silicon/Silicon Structures

2009 ◽  
Vol 609 ◽  
pp. 213-219
Author(s):  
N. Gabouze ◽  
Kahina Ait-Hamouda
Keyword(s):  
Aqueous Solution ◽  
Refractive Index ◽  
Porous Silicon ◽  
Thin Layer ◽  
Spectral Sensitivity ◽  
Optical Filters ◽  
Index Variation ◽  
Silicon Structures ◽  
Optical Behavior ◽  
Silicon Silicon

In this paper, a promising class of optical filters is introduced, based on Al2O3/PS/Si structure. The filters consist of thin layer of aluminium electrochemically oxidized in different aqueous solution, on porous silicon. The spectral sensitivity can be easily varied by Al2O3 thickness. This result is a consequence of refractive index variation of Al2O3 and PS layers, confirmed by ellipsometry measurements.

Basic properties of anodized porous silicon formed under uniform current density

1994 ◽  
Vol 77 (4) ◽  
pp. 97-105
Author(s):  
Hidekazu Aoyagi ◽  
Akira Motohashi ◽  
Akira Kinoshita ◽  
Tomoyoshi Aono ◽  
Akinobu Satoh
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Basic Properties ◽  
Uniform Current

scholarly journals Significant photoinduced refractive index change observed in porous silicon Fabry–Pérot resonators

2000 ◽  
Vol 76 (15) ◽  
pp. 1990-1992 ◽  
Author(s):  
Morio Takahashi ◽  
Yuichi Toriumi ◽  
Takahiro Matsumoto ◽  
Yasuaki Masumoto ◽  
Nobuyoshi Koshida
Keyword(s):  
Refractive Index ◽  
Porous Silicon ◽  
Refractive Index Change ◽  
Index Change ◽  
Fabry Perot

Structural, Surface Morphological and Photoluminescence Properties of Nanostructured Porous Silicon Material for Optoelectronics Application

2012 ◽  
Vol 584 ◽  
pp. 290-294 ◽  
Author(s):  
Jeyaprakash Pandiarajan ◽  
Natarajan Jeyakumaran ◽  
Natarajan Prithivikumaran
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Light Emission ◽  
Electrochemical Etching ◽  
Light Emitting Diode ◽  
Radiative Transition ◽  
Sem Images ◽  
Optoelectronic Application ◽  
Gap Opening ◽  
P Type

The promotion of silicon (Si) from being the key material for microelectronics to an interesting material for optoelectronic application is a consequence of the possibility to reduce its device dimensionally by a cheap and easy technique. In fact, electrochemical etching of Si under controlled conditions leads to the formation of nanocrystalline porous silicon (PS) where quantum confinement of photo excited carriers and surface species yield to a band gap opening and an increased radiative transition rate resulting in efficient light emission. In the present study, the nanostructured PS samples were prepared using anodic etching of p-type silicon. The effect of current density on structural and optical properties of PS, has been investigated. XRD studies confirm the presence of silicon nanocrystallites in the PS structure. By increasing the current density, the average estimated values of grain size are found to be decreased. SEM images indicate that the pores are surrounded by a thick columnar network of silicon walls. The observed PL spectra at room temperature for all the current densities confirm the formation of PS structures with nanocrystalline features. PL studies reveal that there is a prominent visible emission peak at 606 nm. The obtained variation of intensity in PL emission may be used for intensity varied light emitting diode applications. These studies confirm that the PS is a versatile material with potential for optoelectronics application.

scholarly journals Refractive index evaluation of porous silicon using Bragg reflectors

2018 ◽  
Vol 64 (1) ◽  
pp. 72 ◽  
Author(s):  
D. Estrada-Wiese ◽  
J.A. Del Río
Keyword(s):  
Refractive Index ◽  
Porous Silicon ◽  
Simple Procedure ◽  
Merit Function ◽  
Refractive Indices ◽  
Bragg Reflectors ◽  
Photonic Bandgaps ◽  
Photonic Structures ◽  
Index Evaluation

There are two main physical properties needed to fabricate 1D photonic structures and form perfect photonic bandgaps: the quality of thethickness periodicity and the refractive index of their components. Porous silicon (PS) is a nano-structured material widely used to prepare 1Dphotonic crystals due to the ease of tuning its porosity and its refractive index by changing the fabrication conditions. Since the morphologyof PS changes with porosity, the determination of PS’s refractive index is no easy task. To find the optical properties of PS we can usedifferent effective medium approximations (EMA). In this work we propose a method to evaluate the performance of the refractive index ofPS layers to build photonic Bragg reflectors. Through a quality factor we measure the agreement between theory and experiment and thereinpropose a simple procedure to determine the usability of the refractive indices. We test the obtained refractive indices in more complicatedstructures, such as a broadband Vis-NIR mirror, and by means of a Merit function we find a good agreement between theory and experiment.With this study we have proposed quantitative parameters to evaluate the refractive index for PS Bragg reflectors. This procedure could havean impact on the design and fabrication of 1D photonic structures for different applications.

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