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    A systematic study on MOS type radiation sensors
    (Elsevier, 2007) Yilmaz, Ercan; Kaleli, Buket; Turan, Rasit
    Radiation sensors based on metal oxide semiconductor (MOS) structure are useful because of their superior sensitivity as well as excellent compatibility with the existing microelectronic technology. In this paper, a systematic study of MOS capacitors built on p- and n-type Si substrates with different SiO2 thicknesses (10 nm, 50 nm, 100 nm and 240 nm) is presented. MOS device response to gamma radiation up to 256 Gray have been studied from the sensor application point of view. Variation of the radiation induced device response with oxide thickness, substrate type, applied bias and post annealing have been measured and discussed. Radiation induced charge in MOS devices is shown to be a strong function of the oxide thickness as expected. Application of a positive bias to the gate is found to enhance the device sensitivity for both n- and p-type devices. This is explained in terms of the involvement of the interface states in the sensing process. Devices have also been studied after repeated cycles of irradiation and annealing treatment under hydrogen atmosphere. Each cycle consists of gamma irradiation with 60 Gray dose and an anneal at 200 degrees C for 30 min. The charging-discharging mechanism during these cycles is discussed. (c) 2007 Elsevier B.V. All rights reserved.
  • Küçük Resim
    Öğe
    Temperature cycling of MOS-based radiation sensors
    (Elsevier Science Sa, 2008) Yilmaz, Ercan; Turan, Rasit
    We have studied dosimetric characteristics, linearity and performance of MOS structures as radiation sensors. This was performed by analyzing the correlation between irradiation dose and the shift in flat band voltage of MOS capacitors which were tested against gamma and beta radiations. Devices have been studied after repeated cycles of irradiation and annealing treatment under hydrogen and nitrogen ambient. Each cycle consists of gamma irradiation with 60 Gray-dose and an anneal at 200 degrees C for 30 min. Results obtained by high frequency C-V methods show that irradiation-annealing cycle correlates with the recovery of the measured signal. The charging-discharging mechanism during the cyclic treatment is discussed. The variation of the interface state density during the irradiation-annealing cycle was studied with a model based on conductance-voltage measurements. (c) 2007 Elsevier B.V. All rights reserved.