Search results for "Detectors"
showing 10 items of 2229 documents
High Performance Solar Blind Detectors based on AlGaN grown by MBE and MOCVD
2004
ABSTRACTSolar blind detectors based on AlGaN grown by Molecular Beam Epitaxy and Metal Organic Vapor Phase Epitaxy have been fabricated and characterized. Metal Semiconductor Metal (MSM) detectors and vertical Schottky detectors have been realized, with a design that allows back side illumination. The growth was optimized in order to improve the layer quality, avoid crack formation, and provide the best detector performance. The technological process was also optimized in order to reduce the dark currents and improve the spectral rejection ratio, which is a key factor for solar blind detection. As a result, a rejection ratio of 5 decades between the UV (below 300 nm) and 400 nm, and a steep…
Responsivity measurements of 4H-SiC Schottky photodiodes for UV light monitoring
2014
We report on the design and the electro-optical characterization of a novel class of 4H-SiC vertical Schottky UV detectors, based on the pinch-off surface effect and obtained employing Ni2Si interdigitated strips. We have measured, in dark conditions, the forward and reverse I–V characteristics as a function of the temperature and the C–V characteristics. Responsivity measurements of the devices, as a function of the wavelength (in the 200 – 400 nm range), of the package temperature and of the applied reverse bias are reported. We compared devices featured by different strip pitch size, and found that the 10 μm device pitch exhibits the best results, being the best compromise in terms of fu…
Charge Transport Properties in CZT Detectors Grown by the Vertical Bridgman Technique
2010
Great efforts are being presently devoted to the development of CdTe and CdZnTe detectors for a large variety of applications, such as medical, industrial, and space research. We present the spectroscopic properties of some CZT crystals grown by the standard vertical Bridgman method and by the boron oxide encapsulated vertical Bridgman method, which has been recently implemented at IMEM-CNR (Parma, Italy). By this technique the crystal is grown in an open quartz crucible fully encapsulated by a thin layer of liquid boron oxide. This method prevents contact between the crystal and the crucible thereby allowing larger single grains with a lower dislocation density to be obtained. Several mono…
Affordable, ultra-broadband coherent detection of terahertz pulses via CMOS-compatible solid-state devices
2017
We demonstrate the first fully solid-state technique for the coherent detection of ultra-broadband THz pulses (0.1-10 THz), relying on the electric-field-induced second-harmonic generation attained in integrated CMOS-compatible devices.
Responsivity measurements of silicon carbide Schottky photodiodes in the UV range
2014
We report on the design and the electro-optical characterization of new classes of 4H-SiC Schottky UV detectors, fabricated employing Ni 2 Si interdigitated strips. We have measured, in dark conditions, the forward and reverse I-V characteristics as a function of temperature and C-V characteristics. Responsivity measurements of the devices, as function of wavelength in the UV range, of package temperature and of applied reverse bias are reported. We also compared devices featuring different strip pitch sizes, discussing their performances, and found the device exhibiting best results.
Numerical study of surface waves generated by low frequency EM field for silicon refinement
2018
One of the most perspective methods to produce solar grade silicon is refinement via metallurgical route. The most critical part of this route is refinement from boron and phosphorus due to high segregation coefficients. One possible approach to remove boron is use of reactive gas on surface of silicon melt. An approach of creating surface waves on silicon melt's surface is proposed in order to enlarge its area and accelerate removal of boron via chemical reactions. This paper focuses on numerical analysis of surface wave creation by means of low frequency magnetic field. Frequency of magnetic field and its amplitude significantly change the character of surface waves with most changes occu…
Integrated Optical Amplifier-Photodetector on a Wearable Nanocellulose Substrate
2018
Flexible optoelectronics has emerged as an outstanding platform to pave the road toward vanguard technology advancements. As compared to conventional rigid substrates, a flexible technology enables mechanical deformation while maintaining stable performance. The advantages include not only the development to novel applications, but also the implementation of a wearable technology directly in contact with a curved surface. Here the monolithic integration of a perovskite‐based optical waveguide amplifier together with a photodetector on a nanocellulose substrate is shown to demonstrate the feasibility of a stretchable signal manipulation and receptor system fabricated on a biodegradable mater…
Failure of topological rigidity results for the measure contraction property
2014
We give two examples of metric measure spaces satisfying the measure contraction property MCP(K,N) but having different topological dimensions at different regions of the space. The first one satisfies MCP(0,3) and contains a subset isometric to $\mathbb{R}$, but does not topologically split. The second space satisfies MCP(2,3) and has diameter $\pi$, which is the maximal possible diameter for a space satisfying MCP(N-1,N), but is not a topological spherical suspension. The latter example gives an answer to a question by Ohta.
Design for a high resolution electron energy loss microscope.
2019
International audience; An electron optical column has been designed for High Resolution Electron Energy Loss Microscopy (HREELM). The column is composed of electron lenses and a beam separator that are placed between an electron source based on a laser excited cesium atom beam and a time-of-flight (ToF) spectrometer or a hemispherical analyzer (HSA). The instrument will be able to perform full field low energy electron imaging of surfaces with sub-micron spatial resolution and meV energy resolution necessary for the analysis of local vibrational spectra. Thus, noncontact, real space mapping of microscopic variations in vibrational levels will be made possible. A second imaging mode will al…
Comparison of two portable solid state detectors with an improved collimation and alignment device for mammographic x-ray spectroscopy.
2006
We describe a portable system for mammographic x-ray spectroscopy, based on a 2 X 2 X 1 mm3 cadmium telluride (CdTe) solid state detector, that is greatly improved over a similar system based on a 3 X 3 X 2 mm3 cadmium zinc telluride (CZT) solid state detector evaluated in an earlier work. The CdTe system utilized new pinhole collimators and an alignment device that facilitated measurement of mammographic x-ray spectra. Mammographic x-ray spectra acquired by each system were comparable. Half value layer measurements obtained using an ion chamber agreed closely with those derived from the x-ray spectra measured by either detector. The faster electronics and other features of the CdTe detecto…