Search results for "Photodiode"
showing 8 items of 58 documents
Measurements of Silicon Photomultipliers Responsivity in Continuous Wave Regime
2013
We report on the electrical and optical characterization, in continuous wave regime, of a novel class of silicon photomultipliers fabricated in standard planar technology on a silicon p-type substrate. Responsivity measurements, performed with an incident optical power down to tenths of picowatts, at different reverse bias voltages and on a broad (340–820 nm) spectrum, will be shown and discussed. The device temperature was monitored, allowing us to give a physical interpretation of the measurements. The obtained results demonstrate that such novel silicon photomultipliers are suitable as sensitive power meters for low photon fluxes.
Solar blind detectors based on AlGaN grown on sapphire
2005
Solar blind detectors have been fabricated based on AlGaN heterostructures grown on sapphire by molecular beam epitaxy or chemical vapour deposition. MSM and Schottky detectors were investigated. High performance devices have been obtained thanks to an optimization of the material crystalline quality (including the suppression of cracks) and of the process. We show that the spectral limitations of MSM detectors are dictated by intrinsic phenomena that are analysed in details while the responsivity and detectivity also depends on the technological process with a special emphasis on the geometry of finger and contact pads. One and two dimensional arrays have been fabricated and preliminary re…
Integration of large-area optical imagers for biometric recognition and touch in displays
2021
In recent years there has been an increasing interest to integrate optical sensing in mobile displays, for instance, for biometric fingerprint scanning functionality. There are several routes to incorporate optical fingerprint functionality within the full display area, each with their own benefits and challenges. Here we investigate the different integration routes using large-area, ultra-thin imagers based on organic photodiodes.
Electro-optical characterization of new classes of Silicon Carbide UV photodetectors
2014
In this paper, we present the fabrication process steps and the characterization of 4H-SiC vertical Schottky UV detectors, where interdigitated strips, acting as top metal contacts, have been realized in $\hbox{Ni}_{2}\hbox{Si}$ . These devices exploit the pinch-off surface effect. $I$ – $V$ and $C$ – $V$ characteristics, as functions of temperature, were measured in dark conditions. In addition, we have carried out responsivity measurements, for wavelengths ranging from 200 to 400 nm, at varying package temperature and applied reverse bias. A comparison among devices having different strip pitch sizes has been performed, thus finding out that the 10- $\mu\hbox{m}$ pitch class demonstrates …
Water detection in skin by dual-band photodiodes
2013
Purpose of this study was to develop a simple model for possibilities to detect water in skin by diffuse reflectance spectra. The model is based on comparison of diffuse reflectance spectra when illuminating water sample with LEDs of different wavelengths (1200 nm, and 1450 nm). The illumination LEDs were chosen due to water absorption differences in near-infrared spectral range. For detection, dual-band photodiode DSD2 by Thorlabs was used. Due to differences of water absorption at different wavelengths in the near-infrared spectral region, this correlation could be used for mapping of water content in skin or, in other words, determine relative moisture level in skin. Simple experimental …
Modification of a commercial atomic force microscopy for low-noise, high-resolution frequency-modulation imaging in liquid environment.
2011
A key issue for high-resolution frequency-modulation atomic force microscopy imaging in liquids is minimizing the frequency noise, which requires a detailed analysis of the corresponding noise contributions. In this paper, we present a detailed description for modifying a commercial atomic force microscope (Bruker MultiMode V with Nanoscope V controller), aiming at atomic-resolution frequency-modulation imaging in ambient and in liquid environment. Care was taken to maintain the AFMs original stability and ease of operation. The new system builds upon an optimized light source, a new photodiode and an entirely new amplifier. Moreover, we introduce a home-built liquid cell and sample holder …
THE SILICON PHOTOMULTIPLIER:AN IN-DEPTH ANALYSIS IN THE CONTINUOUS WAVE REGIME
2014
The Silicon Photomultiplier (SiPM) is a novel solid state photon counting detector consisting of a parallel array of avalanche photodiodes biased beyond their breakdown voltage. It has known a fast development in the last few years as a possible alternative to vacuum photomultiplier tubes (PMTs) and conventional avalanche photodiodes (APDs). Indeed, current research in photodetectors is directed toward an increasing miniaturization of the pixel size, thus both improving the spatial resolution and reducing the device dimensions. SiPMs show high photon detection efficiency in the visible and near infrared range, low power consumption, high gain, ruggedness, compact size, excellent single-phot…
Responsivity measurements of SiC photodiodes
2014
We investigated the technical features of three novel classes of 4H-SiC vertical Schottky UV photodiodes (henceforth, named SiC8, SiC10, SiC20) employing Ni2Si interdigitated strips whose pitch size is 8, 10 and 20 µm respectively [1] and based on the pinch-off surface effect.