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Doctors of Sciences

Ahmadov Farid Ibrahim oglu

Ahmadov Farid Ibrahim ogluPlace of birth: Baku, Azerbaijan

Date of birth: 01.04.1983

Education: Baku State University, Faculty of Physics

Scientific degree: Doctor of Physical Sciences

Title: Associate professor

Topic of PhD thesis:
- specialty code: 2225.01
- specialty name: Radiation materials science
- topic name: Investigation radiation hardness of micro-pixel avalanche photodiode based on silicon

Topic of doctoral thesis:
- specialty code: 2225.01
- specialty name: Radiation materials science
- topic name: Development of new micro pixel avalanche photodiodes, investigation of their physical properties and application in radiation spectrometer

Total number of printed scientific publications: 60
- number of scientific publications printed abroad: 25
- number of papers published in journals indexed and abstracted in international databases: 24

Number of patents and certificates of authorship: 1

Staff training:
- number of PhD: 1

Basic scientific achievements:
1. A new deep-buried MAPD photodiode with improved guard ring stop-channel and pixel size is developed and tested. In comparison with MAPD-3NK, the new MAPD-3NM type photodetectors have a 19 % low operating voltage, 5.2 times less dark current and 80 % more avalanche gain. It was obtained that the photodetection efficiency of new developed MAPD photodiode is 5 times higher than analogs.
2. A new structure of MAPD has been developed to improve photodiodes parameters, increase gain, photodetection efficiency and reduce cost. The proposed device uses a series of micro p-n junctions as quenching resistors. It has been found that the new MAPD photodiodes can exceed their analogs by 50 % in terms of performance.
3. A new iterative model has been developed to accurately describe the mechanism of operation of MAPD type photodiodes, taking into account the resistance of the depletion region. It has been found that the gain of MAPD type photodiodes can be doubled depending on the depletion region's resistance.
4. It was found that the rising time of the MAPD photodiodes can be got with increasing the overvoltage to 4 V and the parasitic capacity to 1 % of the pixel.
5. A new gamma spectrometer has been developed based on MAPD-3NK and an inorganic scintillator. It was found that when registering gamma radiation energy of 26.3 keV - 1.33 MeV, this detector exceeds its analog by 34 % in energy resolution and these detectors are linear up to 4.44 MeV.
6. The effect of gamma radiation with an energy of ≈ 1.25 MeV on the dark current, breakdown voltage, capacitance, and energy resolution was studied. It was found that after irradiation a dark current, the energy resolution increased by 15 times and energy resolution by 8.7 %, the capacitance and breakdown voltage remained constant with an accuracy of 5 %.
7. The effect of ~7x108 alpha/cm2 dose of 4.8 MeV alpha particles and 1x1011proton/cm2 dose of 150 MeV protons on the physical properties of MPSF type photoreceptors was studied. As a result of irradiation with alpha particles, the dark current of the diode increased by ~90 times, and the amplification factor decreased by 88%. During proton irradiation, the dark current of the diode a ~102 times increased and gain decreased by 92%. It was determined that due to radiation defects, the holes formed in the first epitaxial layer of MPSF diodes are directly directed towards the anode without participating in the avalanche process as a result of the special distribution of the electric field. The generation and capture centers formed in the second epitaxial layer lead to the change of the dark current and the amplification factor.
8. A new method has been developed that allows studying the amplification factor of MAPD diodes at voltages lower and higher than the breakdown voltage. The proposed new method allows determining the change of the amplification factor of MPSF diodes in a wide range of voltages and the effect of radiation on the amplification factor, unlike the existing weak light method.
9. The principle of operation of new type MAPD diodes with short recovery time is defined. It is shown that at a certain value of the voltage applied in the opposite direction to this type of MAPD diode, the volume of the first p-type epitaxial layer is completely covered by the depletion region, and the volume of the carrier region reaches n+-type pixels. At a high voltage value, the pixels and the second epitaxial layer volume are completely depleted. The Avalanche process takes place at the border of n+-type centers with the second epitaxial layer. Choosing the optimal surface charge density (1.3×1012atom/cm2) of dopant atoms in n+-type pixel centers leads to a sharp decrease in the height of the potential barrier, as well as the recovery time. The recovery time of the proposed MAPD diode is 2.6×104 times smaller than the previous type of MAPD diode and allows recording higher frequency signals (>20MHs).

Main place of work and its address:
Institute of Radiation Problems of the Ministry of Science and Education of the Republic of Azerbaijan, AZ1143, B.Vakhabzadeh str., 9, Baku, Azerbaijan Republic

Position: Head of Laboratory

Office phone: (+99451) 4200820
Mobile: (+99451) 4200820