The LYRA Instrument Onboard PROBA2: Description and In-Flight Performance

The Large Yield Radiometer (LYRA) is an XUV-EUV-MUV (soft X-ray to mid-ultraviolet) solar radiometer onboard the European Space Agency PROBA2 mission that was launched in November 2009. LYRA acquires solar irradiance measurements at a high cadence (nominally 20 Hz) in four broad spectral channels, from soft X-ray to MUV, that have been chosen for their relevance to solar physics, space weather and aeronomy. In this article, we briefly review the design of the instrument, give an overview of the data products distributed through the instrument website, and describe the way that data are calibrated. We also briefly present a summary of the main fields of research currently under investigation by the LYRA consortium

The detection of ultra-relativistic electrons in low Earth orbit

Aims. To better understand the radiation environment in low Earth orbit (LEO), the analysis of in-situ observations of a variety of particles, at different atmospheric heights, and in a wide range of energies, is needed. Methods. We present an analysis of energetic particles, indirectly detected by the Large Yield RAdiometer (LYRA) instrument on board ESA's Project for On-board Autonomy 2 (PROBA2) satellite as background signal. Combining Energetic Particle Telescope (EPT) observations with LYRA data for an overlapping period of time, we identified these particles as electrons with an energy range of 2 to 8 MeV. Results. The observed events are strongly correlated to geo-magnetic activity and appear even during modest disturbances. They are also well confined geographically within the L=4-6 McIlwain zone, which makes it possible to identify their source. Conclusions. Although highly energetic particles are commonly perturbing data acquisition of space instruments, we show in this work that ultra-relativistic electrons with energies in the range of 2-8 MeV are detected only at high latitudes, while not present in the South Atlantic Anomaly region.Comment: Topical Issue: Flares, CMEs and SEPs and their space weather impacts; 20 pages; 7 figures; Presented during 13th European Space Weather Week, 201

ZnO-Based Ultraviolet Photodetectors

Ultraviolet (UV) photodetection has drawn a great deal of attention in recent years due to a wide range of civil and military applications. Because of its wide band gap, low cost, strong radiation hardness and high chemical stability, ZnO are regarded as one of the most promising candidates for UV photodetectors. Additionally, doping in ZnO with Mg elements can adjust the bandgap largely and make it feasible to prepare UV photodetectors with different cut-off wavelengths. ZnO-based photoconductors, Schottky photodiodes, metal–semiconductor–metal photodiodes and p–n junction photodetectors have been developed. In this work, it mainly focuses on the ZnO and ZnMgO films photodetectors. We analyze the performance of ZnO-based photodetectors, discussing recent achievements, and comparing the characteristics of the various photodetector structures developed to date

Preparation of nanostructure TiO2 materals and fabrication of MSM ultraviolet photodetectors based on Nb doped antase TiO2

随着宽禁带半导体材料与器件技术的快速发展，基于宽禁带半导体的紫外探测器有望取代传统的硅基紫外探测器。TiO2材料主要吸收紫外辐射，对可见光几乎不吸收，制备的探测器紫外光/可见光响应对比度较高，因此具有可见光盲和高紫外探测灵敏度特性。另外，TiO2材料制备工艺相对简单，适合用于制备成本较低的紫外探测器。目前，TiO2基紫外探测器的研究大多采用纯锐钛矿相和金红石相的TiO2薄膜材料。对于纳米结构的TiO2薄膜材料和掺杂的TiO2基光电探测器的制备及其性能还知之甚少，本研究工作的主要内容可以分为两大部分：一、TiO2纳米材料的制备；二、Nb掺杂的TiO2材料的制备和基于Nb掺杂的TiO2光电探测器的...As the grown technology develops rapidly, wide band gap semiconductor will replace Si for the fabrication of photodetectors. TiO2 nearly does not absorb visible light, which makes TiO2-based photodetectors show high sensitivity to UV/visible. What is more, the growth of TiO2 films is simple, which is beneficial to low UV photodetectors manufacture. At the moment, the reported TiO2 based UV photode...学位：工学博士院系专业：物理与机电工程学院_微电子学与固体电子学学号：1982012015390

Zinc Oxide Nanorod Based Ultraviolet Detectors with Wheatstone Bridge Design

This research work, for the first time, investigated metal semiconductor-metal (MSM) zine oxide (ZnO) nanorod based ultra-violet (UV) detectors having a Wheatstone bridge design with a high responsivity at room temperature and above, as well as a responsivity that was largely independent of the change in ambient conditions. The ZnO nanorods which acted as the sensing element of the detector were grown by a chemical growth technique. Studies were conducted to determine the effects on ZnO nanorod properties by varying the concentration of the chemicals used for the rod growth. These studies showed how the rod diameter and the deposition of ZnO nanorods from the solution was controlled by varying the concentration of the chemicals used for the rod growth. Conventional MSM UV detectors were fabricated with ZnO nanorods grown under optimized conditions to determine the dependence of UV response on electrode dimension and rod dimension. These studies gave insights into the dependence of UV response on the width of the electrode, spacing between the electrodes, density of the rod growth, and length and diameter of the rods. The UV responsivity was affected by varying the number of times the seed layer was spin coated, by varying the spin speed of seed layer coating and by varying the annealing temperature of the seed and rod. Based on these studies, optimum conditions for the fabrication of Wheatstone bridge UV ZnO nanorod detectors were determined. The Wheatstone bridge ZnO nanorod UV detectors were fabricated in three different configurations, namely, symmetric, asymmetric, and quasi-symmetric. The transient responses of the symmetric, asymmetric and quasi-symmetric configurations at room temperature and above showed how the response stability differed. At high temperature the responsivity of quasi-symmetric Wheatstone bridge detector configuration did not drop after saturation and the responsivity drifted by 17% to 25% from the room temperature response.The responsivity of quasisymmetric Wheatstone bridge configuration with good temperature stability was 1.16 A/W, while those of conventional MSM UV detectors were approximately 60 A/W. However, the quasi-symmetric Wheatstone bridge with responsivity 1.16 A/W was higher than the commercially available detector having responsivity of only about 0.1 A/W. Though the response of quasi-symmetric Wheatstone bridge detector was higher than the detectors available commercially, the response time was very high. The response time of quasi-symmetric Wheatstone bridge was approximately 159 seconds at room temperature, while that of commercially available detectors is of the order of microseconds. If the quasi-symmetric Wheatstone bridge has to compete with current commercially available detectors, then the response time should be brought down from seconds to microseconds. Based on these studies, an improved design of the quasi-symmetric Wheatstone bridge UV detector with the ZnO rods oriented parallel to the substrate instead of oriented vertical to the substrate was proposed

Development and Empirical Investigation of a Self-Powered UV Detector Based-Microcontroller

شهدت  المجسات الاكترونية  المصنوعة من مادة ثاني اوكسيد التيتانيوم  اهتماما كبيرا نظرا لخواصها الالكترونية الملفته للانتباه وتطبيقاتها المتعددة وخاصة في مجال توليد الطاقة المستدامة الرخيصة الثمن. في هذا البحث استخدمت مادة الخلايا الصبغية الحساسة، المتضمنة في تركيبها مادة التيتانيوم التيتانيوم  في تصنيع مجس لتحسس الاشعة فوق البنفسجية بعد باستخدام عدد من التعديلات على طريقة تصنيعه. لتحسين استقرارية المجس وعزله عن تاثيرات المحيط  الخارجي تم تغليفه بمادة بوليمرية  باستخدام تفنيات التصنيع المايكروي.  تم دراسة المجس لمعرفة خواصه الالكترونية  في محيط مفتوح وكذلك تحت الماء. اظهرت الاختبارات  ان المجس ذو حساسية وسرعة استجابة عاليتين لكل من اشارات الاشعة فوق البنفسجية التماثلية منها والمتقطعة. ولاثبات خاصية  القدرة الذاتية  للمجس تم ربطه مع مسيطر مايكروي بدون استخدام مصدر قدرة لتغذية المجس وايضا بدون مكيف اشارة. كما واظهر المجس قابلية على تمييز الالوان مما يفتح الباب لاستخدامه كمجس لوني.Titanium dioxide Nano particles have been used as a core material for the design of low-cost sustainable power source, the dye sensitized cell. In this work, dye sensitized cell was investigated to be used as a self-powered ultra violet light detector in a data acquisition system. To enhance the detector robustness, the device was sealed using cross-linked photo resist to isolate it from the environmental effects. The detector was tested in air as well as in water to proof its characteristics in various environmental conditions. High responsivity and fast response were achieved for both discrete and continuous ultraviolet (UV) illuminations. To prove the self-powered property of the sensor, it was interfaced to a microcontroller. Our experimental results confirmed that there is no need of intermediate electronics such as signal conditioning in the interfacing circuit. Furthermore, the detector observed obvious selectivity for different light colors. This characteristic makes it candidate for the development of color sensors

Visible-blind and solar-blind ultraviolet photodiodes based on (InxGa1-x)2O3

UV and deep-UV selective photodiodes from visible-blind to solar-blind were realized based on a Si-doped (InxGa1–x)2O3 thin film with a monotonic lateral variation of 0.0035<x<0.83. Such layer was deposited by employing a continuous composition spread approach relying on the ablation of a single segmented target in pulsed-laser deposition. The photo response signal is provided from a metal-semiconductor-metal structure upon backside illumination. The absorption onset was tuned from 4.83 to 3.22 eV for increasing x. Higher responsivities were observed for photodiodes fabricated from indium-rich part of the sample, for which an internal gain mechanism could be identified. VC 2016 AIP Publishing LLC

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