The ion beam induced charge (IBIC) technique is a valuable technique to study the degradation of the charge collection efficiency (CCE) induced by radiation damage in semiconductor devices. It offers the advantage of providing a wide range of damage levels generated by ions with different masses and energies in different regions of the same sample, and of using the same or different ions to probe the CCE degradation. This paper describes an experimental protocol based on IBIC and the relevant interpretative model, which includes the displacement damage dose approach as a special case and provides a general method to evaluate the effective radiation hardness of a material.
We present a systematic study of the growth of polycrystalline diamond thin films on W wires and tips by hot filament assisted chemical vapor deposition for x-ray detection purposes. We carry out correlations between scanning electron microscopy (SEM) observations and micro- Raman spectra, while varying different growth parameters. SEM observations show a uniform covering of the substrate, with growth rates ranging from 0.5 to 1.5 micrometers /h. All (mu) - R spectra show a well defined diamond peak at 1330.8-1333.7 cm-1 together with abroad structure at 1400-1600 cm-1 and a luminescence background extending over the whole scanned range. A close analysis shows that best quality is obtained with the lowest diameter substrates, at the lowest CH4 concentration and at a low pressure. Some depositions have been studied as x-ray detectors and their sensitivity at low energy and 6 MeV beam evaluated, showing a good response with respect to standard ionization chambers.
KEYWORDS: Sensors, Electrons, Spectroscopy, Monte Carlo methods, Electric field sensors, Gamma radiation, Sensor performance, Computer programming, Picosecond phenomena, Computer simulations
Simulations of spectroscopic performances of CdTe detectors by means of a Monte Carlo code have been recently reported. The computer code was demonstrated to be an extremely useful tool in simulating the spectral response of CdTe to gamma rays and in understanding the detailed effects of physical and electronic parameters on the experimental performances. In the present work, the attention is focused on the various aspects of the CdTe response to Co gamma rays, in an energy range which is extremely interesting for practical applications of CdTe spectroscopy. Spectra are presented for different experimental conditions particularly in connection with the rise time distributions and with the spatial distribution of the electric field in the detector. A precise correlation is established between the energy distribution and the pulse rise time distribution: the spectra obtained by a selection of a particular rise time interval are presented and discussed, and the conditions for reaching the best energy resolution are indicated. These conditions depend on the material quality and on the electrical field distribution.
A study concerning the use of a 1 cm2 p-i-n (alpha) -Si:H structure coupled to a 1 cm3 CsI(Tl) scintillator is presented and discussed as a survey meter in the range from 20 to 125 keV x ray peak energy. A particular mesa etch, coupled with standard photolithography, lowers dark current in the pA region, allowing the use of the detector in the photovoltaic mode. In this work, we describe the details of detector fabrication, the various steps of detector simulation in order to look for detector performance improvements, and the different stages of detector testing in the reported energy range. For each energy, the linearity of the detector response as a function of the dose rate has been accurately measured and compared with standard ionization chambers of different volumes. Finally, the effective energy reconstruction and the instrument calibration is presented and discussed. Wearing-on applications, similar to film badges, are envisaged and possible solutions are introduced and discussed.
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