OSE Dissertation Defense by Mr. Farnood Mirkhosravi on Gamma and Neutron Irradiation Impacts on Ga-polar and N-polar GaN based diodes

Departmental News

Dr. Pinghan Chu

Posted: April 26, 2022

Date: Monday, May 2, 2022

Time:  2:00 PM - 3:30 PM

Location:  at CHTM, Room 103


Dr. Daniel Feezell, Committee Chair, UNM ECE Department
Dr. Ganesh Balakrishnan, UNM ECE Department
Dr. Payman Zarkesh-Ha, UNM ECE Department

Dr. Azaree Lintereur, Nuclear Engineering Department at Penn State Univ.


III-nitride material (GaN) shows a lot of potential for next generation power electronics. This material is advantageous due to their wide-bandgap, high electron mobility, high thermal and mechanical stability, small form factor, and higher radiation tolerance. The higher radiation tolerance make the GaN based devices more attractive for harsh-environment applications, like aerospace, nuclear reactor and fusion facilities, particle accelerators, and post-detonation environments applications. 

GaN due to its unique crystal structure, can be grown in different orientations and can provide specific advantageous in electronic and optoelectronic devices. While the Ga-polar orientation of GaN has been widely investigated for its proprieties, there are still rooms to study other orientations. The optical and electrical characteristics of GaN based diodes are studied on Ga-polar and N-polar orientation in this thesis. The opposite polarity, different defect, and impurity incorporation in these two orientation results in different behaviors after gamma and neutron irradiation these devices. Current-voltage, circular transfer line method, capacitance-voltage, RF measurements are mainly used to study the diodes characteristics due to gamma and neutron irradiation. The study shows that Ga-polar and N-polar GaN Schottky diodes exhibit significant and different changes in electrical behavior after both gamma and neutron irradiation. The origin of the different behaviors is attributed to the fundamental differences between the Ga-polar and N-polar orientations, such as their opposite polarization and differences in impurity incorporation, defect types, and surface reactivity.