The effect of oxidation on physical properties of porous silicon layers for optical applications

Aminosilane functionalizations of mesoporous oxidized silicon for oligonucleotide synthesis and detection

“…PSi samples 'as etched' are characterized by SSA values of about 100 m 2 g 21 measured by the Brunauer-Emmett-Teller (BET) method [8]; the KOH process induces an increase in porosity of about 6 per cent corresponding to an increase in SSA to 106 m 2 g 21 , quantified by spectroscopic reflectivity (50 nm blue shift of the microcavity spectra, data not shown here). On the contrary, thermal oxidation decreases SSA by 60 per cent (from 106 to 43 m 2 g 21 ), owing the isotropic silica growth also into the pores [18]. PSi-L a,b SSA values (shown in rsif.royalsocietypublishing.org J R Soc Interface 10: 20130160 table 1) have been calculated by applying a simplified model based on the cylindrical shape of the pores taking into account the thickness of silane layer on the pore walls (0.7 nm for APTES and 0.2 nm for APDMES).…”

“…This process is reflected in a blue shift (%70 nm) of PSi multilayer reflectivity spectra, as silica has a lower value of refractive index (1.4 compared with 3.4 of silicon). Thermal oxidation also causes a decrease of pore diameter (D) of about 30 per cent, from 23 to 15 nm: the phenomenon is due to the isotropic silica expansion [18]. Thermally oxidized PSi structures were then silanized.…”

The Influence of Heating Treatment on Physical Properties of Porous Silicon

“…rectification ratio meaning the ratio between forward current to the reverse Current, it for as prepared was equal to 5 ,With increase oxidation time the rectification ratio increase and reach to optimum value about 21 at oxidation time (30 sec). this increased in rectification factor is attributed to the formation a thin oxide layer between AL metal and Si [7] also attributed to formation of an isotope heteojunction ,after that time the rectification ratio will be decreased is due to the defect formed by the sympathize silicon-oxygen structure in a very thin oxide layer and they would act as tunneling center, for oxidation time is longer than (30 sec) the oxide layer is thicker the tunneling probability of photo carriers and the thermal generated carriers through the oxide layer are reduced and hence the dark current to reduced [8]. The oxide thickness is estimated by using equation for high resistivity n-type for silicon [9 ].…”

Porous Silicon Integrated Photonic Devices for Biochemical Optical Sensing

“…In particular, the mean value of the pores width from 18 nm becomes 13 nm. Since the pores density is the same and the pore size decreased, the porosity after oxidation is lower than the porosity before oxidation (Pirasteh et al, 2006). The relationship between the porosities of a PSi layer before and after the thermal oxidation is expressed by the equation:…”

“…6. SEM images of p + PSi layer (a) and p+ PSi layer pre-oxidized at 300°C for one hour following by an oxidation step at 900 °C in wet O 2 for 1 hour (b) (Pirasteh et al, 2006).…”