L. Zeni

AN ELECTRICALLY CONTROLLED BRAGG REFLECTOR INTEGRATED IN A RIB SILICON ON INSULATOR WAVEGUIDE

In this letter, we present a novel structure for light amplitude modulation based on a lateral p-i-n diode combined with a Bragg reflector which transforms the phase shift induced by the plasma dispersion effect in the intrinsic region of the diode into a voltage controlled variation of the reflectivity of the Bragg mirror. Numerical simulations show a modulation depth of 50% achieved in about 12 ns with a power dissipation of 4.0 mW and an insertion loss of 1.0 dB. The device is demonstrated to be very attractive in terms of power dissipation as compared to a Mach–Zehnder interferometer occupying the same area on chip.

An optical technique to measure the bulk lifetime and the surface recombination velocity in silicon samples based on a laser diode probe system

Abstract A high sensitivity, pump–probe optical method to measure the bulk minority-carrier lifetime and surface recombination velocity in silicon is proposed. A pig-tailed 1.55xa0μm CW laser diode is used to detect the transient of the excess carriers generated by a short Nd:YAG laser pulse. The probe beam is launched parallel to the sample surface while the pump beam uniformly illuminates the sample perpendicular to its surface. Separation between bulk lifetime and surface recombination velocity is achieved by performing the measurement on samples of different thickness. Experimental results indicate that separation of bulk and surface contribution is feasible in a wide range of surface recombination velocities thus making this method suitable to investigate the effects of surface passivation techniques.

Contactless characterization of the recombination process in silicon wafers: Separation between bulk and surface contribution

Abstract Taking advantage of a new interferometric technique and relying on a suitable model for the electron-hole transient recombination process, we propose an all optical measurement procedure able to separate the bulk contribution from the surface contribution when measuring the recombination lifetime in silicon wafers. In particular our technique is able to measure the bulk lifetime and the surface recombination velocity at low injection levels and allows the characterization of bulk silicon wafers and surface passivation techniques. The validity of our approach is confirmed by various numerical simulations and several experimental results.

Interferometric measurement of electron-hole pair recombination lifetime as a function of the injection level

The authors describe an interferometric technique for the measurement of the recombination lifetime of electron-hole pairs as a function of their concentration, which can be measured with an error smaller than 10%. In addition, the approach is much more sensitive than the other optical methods described in the literature.<<ETX>>

Recombination centers identification in very thin silicon epitaxial layers via lifetime measurements

A new test structure for the recombination lifetime profile measurement has been designed and applied, for the first time, to characterize very thin (4 /spl mu/m) silicon epitaxial layers. The results of our analysis have shown how the lifetime behavior, at room temperature, is clearly position dependent its value being influenced by different recombination centers. Moreover, two distinct recombination centers have been identified, the first one related to the dopant (arsenic in our case) and the second one induced by the process steps required to realize the test structure itself.

A thermo-stabilized flow cell for surface plasmon resonance sensors in D-shaped plastic optical fibers

The first example of an optical sensor platform based on surface plasmon resonance (SPR) in a plastic optical fiber (POF) integrated into a thermo-stabilized flow cell for biochemical sensing applications is proposed. In this work, an IgG/anti-IgG assay was implemented as model bioassay, with the IgG biolayer deposited on the sensor gold surface and the biological target, anti-IgG, transported through a new thermo-stabilized flow cell. The experimental results show that the proposed device can be successfully used for label-free biochemical sensing. This complete optical sensor system can be used for the future reduction of the device cost and dimension, with the possibility of integrating the POF-SPR sensing platform with microfluidic and optoelectronic devices.

SPR sensors in POF: a new experimental configuration for extended refractive index range and better SNR

In this work we present a new low cost SPR (Surface Plasmon Resonance) sensor configuration based on efficient higher-order mode filtering in plastic multimode fibers, using a tapered POF (Plastic Optical Fiber) after the sensor system, without decreasing the sensitivity of the sensor. In particular, we present the experimental results obtained with this new configuration. The experimental results have shown as the tapered POF after the sensor system influences the performances in terms of refractive index range and Signal-to-Noise Ratio (SNR).

Optical measurement of effective recombination lifetime in silicon epitaxial layers

In this letter we present a novel all-optical pump-probe technique for the measurement of effective recombination lifetime in silicon epitaxial layers. The procedure is based on the measurement of the variation of the attenuation coefficient due to optically injected free carriers of a planar dielectric waveguide defined by the epitaxial layer cladded between the substrate and the air. Perturbation theory is used to take into account nonuniform refractive index distribution due to nonzero surface recombination. The measurement technique is validated by both numerical simulation and experimental results.

Spatial distribution of recombination centers in electron irradiated silicon epitaxial layers

Taking advantage of a suitable three terminals test structure, we analyze the effects of electron irradiation in silicon epitaxial layers, through the measurement of the recombination lifetime profile. Furthermore, by means of an appropriate temperature scanning we measure the energy levels of the recombination centers induced by the irradiation itself.