39 research outputs found
SiC detectors: A review on the use of silicon carbide as radiation detection material
Silicon Carbide (SiC) is a wide bandgap semiconductor with many excellent properties that make it one of the most promising and well-studied materials for radiation particle detection. This review provides an overview of the main advantages in the use of SiC detectors and the current state of research in this field. Key aspects related to material properties, growth techniques, doping, defects, electrical contacts, and characterization methods are summarized, with particular emphasis on how these can be related to detector performance. The most recent and significant experimental results on the use of SiC diodes for the detection of electrons, protons, alpha, ions, UV radiation, x/γ-rays, and neutrons are discussed. The effects of high temperature operation and radiation damage on detector performance are outlined
GaN radiation detectors for particle physics and synchrotron applications
In this thesis the work will focus on the development of wide band gap radiation detectors for radiation hard, biological and monitoring applications. Gallium nitride (GaN) was investigated as a radiation hard particle detector and as an UV light detector while the properties of single crystal diamond as a soft x-ray beam position monitor were assessed. Photolithographic processes were used to produce Schottky pad detectors of 1 mm diameter on three epitaxial GaN wafers grown on a sapphire substrate. Two of the wafers were obtained from Tokushima University, Japan and had an epitaxial thickness of 2.5 mum while the third GaN wafer was grown by Lumilog, France and had an epitaxial thickness of 12 mum. Devices were irradiated with 24 GeV/c protons and neutrons (1 MeV equivalent) to fluences of 10[14], 10[15], 2x10[15], 5x10[15] and 10[16] particles cm[-2] and the macroscopic properties characterised through current-voltage (I-V), capacitance-voltage (C-V) and charge collection efficiency measurements using alpha particles. The leakage currents of the irradiated GaN detectors were in some cases orders of magnitude smaller than the unirradiated devices. This phenomenon has also been observed in other irradiated wide band gap semiconductors, SiC and diamond. The maximum CCE of the thin epitaxial GaN detector was 97% while the thicker epitaxial GaN detector exhibited a maximum CCE of 53%. Irradiation with protons and neutrons led to a dramatic reduction in the CCE of the GaN detectors. For example, the CCE of one of the thin epitaxial GaN detectors dropped from 97% pre-irradiation to 40% after irradiation to 10[16] neutrons cm[-2] and 13% after irradiation to 10[16] protons cm[-2]. The drop in CCE of the thicker epitaxial material was less pronounced however the devices irradiated to the highest fluences, 1016 neutrons cm[-2] and 10[16] protons cm-2 exhibited CCEs of only 17% and 25% respectively. Attempts were made at identifying and understanding the microscopic as-grown and radiation-induced defects that determine the macroscopic characteristics of the GaN detectors. The microscopic properties of unirradiated and irradiated GaN detectors were evaluated using photoluminescence (PL), contact photoconductivity (CPC) and thermally stimulated current (TSC) techniques. Both PL and CPC measurements of the irradiated devices revealed a substantial increase in non-radiative recombination. In particular the intensity of the yellow band PL peak is significantly reduced after irradiation to 10[16]particles cm[-2]. TSC measurements of the GaN detectors revealed several competing complicated transport mechanisms. Thermal activation energies of 0.16-0.2, 0.27-0.32, 0.36-0.45 and 0.73-0.74 eV were extracted from neutron irradiated thin epitaxial GaN detectors. Dry etching of various GaN materials was done in a inductively coupled plasma (ICP) machine. The GaN samples were etched in order to produce ohmic contacts to the n-GaN buffer layers and to realise a parallel plate capacitor detector geometry. From the current-voltage and capacitance- voltage characteristics of the etched devices the ideality factor, Schottky barrier height and carrier concentration were extracted. The parallel plate capacitor geometry of the etched devices resulted in an increase in charge collection efficiency compared to the unetched devices. This is attributed to better definition of the electric field within the etched devices resulting in significantly improved charge transport
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Wide bandgap semiconductor radiation detectors for extreme environments
Wide bandgap semiconductor photodiodes were investigated for their suitability as radiation detectors for high temperature applications (≥ 20 °C), through measurements, calculations of key parameters of the devices, and relating the results back to the material, geometry of the detectors, environment under which the detectors were investigated, and previously published work. Three families of photodiodes were examined.
4H-SiC vertical Schottky UV photodiodes with Ni2Si interdigitated contacts were characterised for their response under dark and UV illumination. Electrical characterisation up to 120 °C and room temperature responsivity measurements (210 nm to 380 nm) suggested that the devices could operate at low UV light intensities, even at high visible and IR backgrounds without the use of filters, and at high temperatures.
4H-SiC Schottky photodiode detector arrays with planar thin NiSi contacts were investigated for X-ray (≤ 35 keV) detection and photon counting spectroscopy at 33 °C. The electrical characterisation of the devices up to 140 °C and subsequent analysis suggested that the devices are likely to operate as high temperature X-ray spectrometers.
Results characterising GaAs p+-i-n+ mesa photodiode detectors for their room temperature visible and near infrared responsivity (580 nm to 870 nm), as well as their high temperature (≤ 60 °C) X-ray detection performance (at 5.9 keV) are presented. GaAs p+-i-n+ mesa photodiodes were also shown to be suitable for β- particle (electron) spectroscopy and X-ray fluorescence spectroscopy (≤ 21 keV) at 33 °C.
The X-ray and electron spectroscopic measurements were supported by a comprehensive treatment of the noise components in charge sensitive preamplifiers. Calculations showed the potential benefits of using a SiC, rather than Si, JFET as the input transistor of such a preamplifier operating at high temperatures. The spectroscopic measurements, using both the 4H-SiC and GaAs photodiodes, are presented along with noise analysis to detangle the different noise components present in the reported spectrometers, identify the dominant source of noise, and suggest potential improvements for future spectrometers using the reported devices
Feature Papers in Electronic Materials Section
This book entitled "Feature Papers in Electronic Materials Section" is a collection of selected papers recently published on the journal Materials, focusing on the latest advances in electronic materials and devices in different fields (e.g., power- and high-frequency electronics, optoelectronic devices, detectors, etc.). In the first part of the book, many articles are dedicated to wide band gap semiconductors (e.g., SiC, GaN, Ga2O3, diamond), focusing on the current relevant materials and devices technology issues. The second part of the book is a miscellaneous of other electronics materials for various applications, including two-dimensional materials for optoelectronic and high-frequency devices. Finally, some recent advances in materials and flexible sensors for bioelectronics and medical applications are presented at the end of the book
Miniaturized Silicon Photodetectors
Silicon (Si) technologies provide an excellent platform for the design of microsystems where photonic and microelectronic functionalities are monolithically integrated on the same substrate. In recent years, a variety of passive and active Si photonic devices have been developed, and among them, photodetectors have attracted particular interest from the scientific community. Si photodiodes are typically designed to operate at visible wavelengths, but, unfortunately, their employment in the infrared (IR) range is limited due to the neglectable Si absorption over 1100 nm, even though the use of germanium (Ge) grown on Si has historically allowed operations to be extended up to 1550 nm. In recent years, significant progress has been achieved both by improving the performance of Si-based photodetectors in the visible range and by extending their operation to infrared wavelengths. Near-infrared (NIR) SiGe photodetectors have been demonstrated to have a “zero change” CMOS process flow, while the investigation of new effects and structures has shown that an all-Si approach could be a viable option to construct devices comparable with Ge technology. In addition, the capability to integrate new emerging 2D and 3D materials with Si, together with the capability of manufacturing devices at the nanometric scale, has led to the development of new device families with unexpected performance. Accordingly, this Special Issue of Micromachines seeks to showcase research papers, short communications, and review articles that show the most recent advances in the field of silicon photodetectors and their respective applications
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Silicon carbide and diamond radiation detectors
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Advances in Perovskites for Photovoltaic Applications in Space
Perovskites have emerged as promising light harvesters in photovoltaics. The resulting solar cells (i) are thin and lightweight, (ii) can be produced through solution processes, (iii) mainly use low-cost raw materials, and (iv) can be flexible. These features make perovskite solar cells intriguing as space technologies; however, the extra-terrestrial environment can easily cause the premature failure of devices. In particular, the presence of highenergy radiation is the most dangerous factor that can damage space technologies. This Review discusses the status and perspectives of perovskite photovoltaics in space applications. The main factors used to describe the space environment are introduced, and the results concerning the radiation hardness of perovskites toward protons, electrons, neutrons, and gamma-rays are presented. Emphasis is given to the physicochemical processes underlying radiation damage in such materials. Finally, the potential use of perovskite solar cells in extra-terrestrial conditions is discussed by considering the effects of the space environment on the choice of the architecture and components of the devices
Photodetectors
In this book some recent advances in development of photodetectors and photodetection systems for specific applications are included. In the first section of the book nine different types of photodetectors and their characteristics are presented. Next, some theoretical aspects and simulations are discussed. The last eight chapters are devoted to the development of photodetection systems for imaging, particle size analysis, transfers of time, measurement of vibrations, magnetic field, polarization of light, and particle energy. The book is addressed to students, engineers, and researchers working in the field of photonics and advanced technologies