Analysis and TCAD Simulation for C/V, and G/V Electrical Characteristics of Gated Controlled Diodes for the AGIPD of the EuXFEL
The Gated Controlled diodes are an important tool for the characterization of the Si-SiO2 interface with respect to surfaced effects of Si sensors. Gated diodes were fabricated by CiS, Erfurt, Germany on high resistivity (3–4 kΩ cm) <111> oriented n-type silicon material and irradiated by 10 keV X-rays up to 1 GGY at HASYLAB, DESY, Hamburg; the experimental measurements for the extraction of microscopic parameters; fixed oxide charges (Nfixox), interface trap density (Dit), capture cro-sections of Dit (σeff), width of Gaussian σrmsit, and energy level Ec-Eit and surface current (Iox) are performed. The interface states densities (Dit in cm−2 eV−1) have been determined by measurements of the Thermally Dielectric Relaxation Current (TDRC) signal versus energy level (Ec-Eit). The aim is to use extracted parameters in Synopsys TCAD device simulation to reproduce measurement. The purpose of this paper is to analyze experimental measurements on non-irradiated and irradiated gated diode from the electrical characteristics of Al/SiO2/n-Si (MOS) capacitors. The Capacitance-Voltage (C/Vg) and Conductance-Voltage (G/ω/Vg) measurement have been carried out in the frequency range of 10 kHz–800 kHz and bias voltage range of (+3 V) to (−85 V) at room temperature of 293 K. It was found that both C and G/ω of the MOS capacitor was quite sensitive to frequency, and flatband voltage and oxide capacitance decreases with increasing frequency in strong accumulation whereas G increases with frequency. The change of the capacitance in the accumulation region at high frequency is resulting from the presence of high concentration of interface trap density or uncorrected series resistance (Rs) of the bulk Si and the change of the conductance is due to the change of the distribution of the charge carrier at Si-SiO2 interface. In addition, the capacitance and conductance have been corrected at 10 kHz and 800 kHz for the effect of series resistance (Rs) to obtain the real capacitance and conductance of MOS capacitors for non-irradiated and irradiated with 5 MGy. The frequency dependent C/Vg and G/ω/Vg characteristics confirm that the Nfixox, Dit, Ec-Eit, σit (width of Gaussian profile distribution of interface trap) and Rs of the MOS capacitors are an important parameters that strongly influence the electrical properties of MOS capacitors.
The author specially would like to thank the H. Perrey, University of Hamburg for providing data for analysis and E. Fretwurst, R. Klanner for useful discussion and suggestions and constant academic supports during my comparison of simulation and data. The authors would also like to thank the XFEL company for support and also would like to thank to the peoples involved in the development of AGPID for XFEL experiment from DESY (Deutsches Elektronen Synchrotron), PSI (Paul Scherer institute), Switzerland and University of Bonn, Germany for constant interest and support. This work was profited from the infrastructure grant of the Helmholtz Alliance “Physics at the Terascale”.
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