Temat: Silicon Photodiode - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Quality control test of conventional X-Ray systems in Delta State, South-South, Nigeria
Autorzy:: Ijabor, B. O.
Nzotta, C. C.
Omojola, A. D.
Powiązania:: https://bibliotekanauki.pl/articles/1193452.pdf
Data publikacji:: 2021
Wydawca:: Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:: Digital Radiography (DR)
Focus to Image Distance (FID)
Half Value Layer (HVL)
Practical Peak Voltage (PPV)
Quality Assurance
Quality Control
Silicon Photodiode
Opis:: The quality assurance (QA) and quality control (QC) programmes of imaging equipment are key ingredients of a quality system. This study is aimed at measuring X-Ray machine parameters and comparing them with the American Association of Physicists in Medicine (AAPM) report No. 74. Also, this study made comparison with similar articles locally and internationally. The study was conducted in 12 X-Ray unit (A-L) located in Delta State. A MagicMax Universal Basic Unit was used alongside an XR Multidetector (silicon photodiode) to measure dose, dose rate, practical peak voltage (PPV), exposure time, current in milliampere (mA) and quantity (Q) in milliampere seconds (mAs). The XR Multidetector was positioned at 100 cm from the focus to image distance (FID) to make most measurements. Six (6) X-Ray units were above 20 years, accounting for 50% of the total X-Ray units used. 30% of X-Ray units > 20 years failed the QC test, which was 2.3 times higher than X-Ray units < 10 and 10-20 years respectively. On the average, 55% pass mark was achieved in the 12 X-Ray units across the state, while 26.11% of the test could not be done due to bad knobs and other challenges. Two (2) X-Ray units with an average age of 3 years, passed all the test. The study showed that many of the X-Ray units were old and certain machine parameters could not be assessed. The study also reveal that most X-Ray specifications manual were either misplaced or missing. Continuing QC programme is highly recommended in the studied areas.
Źródło:: World Scientific News; 2021, 157; 140-153
2392-2192
Pojawia się w:: World Scientific News
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Azotek krzemu stosowany w technologii planarnych fotodiod wykonanych na bazie InP
Silicon nitride for InP based planar photodiode applications
Autorzy:: Zynek, J.
Hejduk, K.
Klima, K.
Możdżonek, M.
Stonert, A.
Turos, A.
Rzodkiewicz, W.
Powiązania:: https://bibliotekanauki.pl/articles/192312.pdf
Data publikacji:: 2008
Wydawca:: Sieć Badawcza Łukasiewicz - Instytut Technologii Materiałów Elektronicznych
Tematy:: azotek krzemu
PECVD
fotodioda planarna
InP
silicon nitride
planar photodiode
Opis:: Przeprowadzono badania warstw azotku krzemu osadzonych na płytkach z fosforku indu metodą PECVD (Plasma Enhanced Chemical Yapor Deposition) z wykorzystaniem do wytwarzania plazmy dwóch generatorów pracujących na różnych częstotliwościach. Celem badań było ustalenie warunków wytwarzania warstw azotku krzemu stosowanych w technologii planarnych fotodiod wykonanych na bazie InP, w których obszarem absorpcyjnym są studnie kwantowe z InxGa1-xAs. Warstwy azotku krzemu były osadzane w temperaturach pomiędzy 250°C i 300°C. Podstawą do oceny wytworzonych warstw były wyniki badań: ich składu chemicznego, struktury, współczynnika załamania, poziomu naprężeń, rezystywności, wytrzymałości dielektrycznej, stałej dielektrycznej i efektywnej gęstości powierzchniowej ładunków elektrycznych. Stwierdzono, że warstwy osadzane w temperaturze 250°C mają najlepszą strukturę, dobrze spełniają rolę maski w procesie selektywnej dyfuzji cynku, a właściwości elektryczne umożliwiają wykorzystanie ich do pasywacji powierzchni bocznych złącz p-n, pod warunkiem zastosowania odpowiedniego cyklu wygrzewań po procesie osadzania.
Silicon nitride films, deposited on InP wafers by the PECVD (Plasma Enhanced Chemical Vapor Deposition) method, have been investigated in terms of their applicability in the technology of InP based planar photodiodes with the InxGa1-xAs quantum well absorption region. In order to compensate the mechanical stress in the films, the plasma was excited by two radio-frequency sources operating at frequencies of 13,56 MHz and 100 kHz. The films were deposited at different temperatures in the range of 250 - 300°C. The chemical composition of all examined films, determined by the RBS (Rutherford Backscattering Spectrometry) method, is very close to that of stoichiometric Si3N4. The films contain a large amount of hydrogen. The hydrogen content, evaluated by the NRA (Nuclear Reactions Analysis) technique, exceeds 30 %. The silicon nitride films deposited at 300°C have grown much faster on InP wafers than on Si wafers placed beside these and the structure of both films is different. As the films deposited on Si are amorphous with smooth surfaces, the films deposited on InP are heterogeneous with rough surfaces. These last ones exhibit lower Si-N bond concentration, lower refractive index, higher extinction coefficient, lower resistivity and lower dielectric breakdown strength than the films deposited on silicon. Deterioration of the film quality is caused probably by the reaction of phosphorus, released from the InP substrate at the beginning of the deposition process, with deposited SiNx:H. Such films should not be used in the fabrication of InP based planar photodiodes. When the deposition temperature decreases, the properties of silicon nitride films improve. Their structure becomes more homogeneous and the Si-N bond concentration increases. The silicon nitride films deposited on InP at 250°C have the same amorphous structure and the same Si-N bond concentration, determined from FTIR (Fourier Transform Infrared Spectroscopy) absorption characteristics, as the films deposited on silicon. They exhibit the highest refractive index, the lowest extinction coefficient, the highest resistivity and the highest dielectric breakdown strength. These films are continuous, they do not crack during thermal processes and they can be applied as masking layers for the selective Zn diffusion used to form the p-n junctions. Unfortunately the films deposited at 250°C have the highest hydrogen content and the highest effective charge density. These films cannot be applied directly to passivate the p-n junction side surfaces. Measurements of hydrogen depth profiles and of FTIR absorption characteristics have revealed that the amount of hydrogen and of Si-N, Si-H and N-H bonds changed during annealing. An analysis of C-V characteristics of Al/Si3N4:H/InP MIS capacitors containing these films has shown, that annealing of the Si3N4:H films reduced the electronic defect state density at the Si3N4:H/InP interface. It is possible to take advantage of the thermal instability of silicon nitrides deposited by the PECVD method and to reduce the trap state density and the effective charge density by proper annealing processes. These investigations have enabled us to achieve reverse current values as low as 4 - 15 pA at the voltage of - 5 V and 200 - 500 pA at the voltage of -50 V for planar InP diodes with the 320 um diameter p-n junction. A high yield of 90 % is obtained. These results make a good base for development of planar photodiodes with InxGa1-xAs quantum wells inserted into the depletion region of the InP p-n junction.
Źródło:: Materiały Elektroniczne; 2008, T. 36, nr 4, 4; 95-113
0209-0058
Pojawia się w:: Materiały Elektroniczne
Dostawca treści:: Biblioteka Nauki

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