POST GRADUATE SEMINAR SERIES Seminar on “Current Collapse Suppression by Gate Field-Plate in AlGaN/GaN High Electron Mobility Transistors”

Sunday 23 November 2014 For the very first time, Dept. of EEE has organized a seminar series named “Post Graduate Seminar Series” for inspiring the students towards research, of which, seminar on “Current Collapse Suppression by Gate Field-Plate in AlGaN/GaN High Electron Mobility Transistors” by the esteemed speaker Dr. Md. Tanvir Hasan (Faculty, Dept. of EEE) held on 12th November, 2014 in AIUB Auditorium. Post-graduate students with some of the enthusiastic undergraduate students attended program. The students will be highly beneficial with this approach. Mr. Chowdhury Akram Hossain (Assistant Professor, Department of EEE & Special Assistant, OSA) hosted the seminar by welcoming the seminar attendees emphasizing on attending seminars to learn about new inventions and current technologies. After that, Mr. Rinku Basak (Assistant Professor& Head, Postgraduate Program, Department of EEE) talked about process of project & thesis completion and choosing right subjects from the curriculum of MEEE & MTEL. Dr. Md. Tanvir Hasan, the speaker then gave a talk on his PhD research focusing on new gate configuration with GaN based material. Besides this he also encouraged students to pursue research work in material level of electronics. His work was emphasized using Film plate in gate position for better confinement for trapping charge which leads to decrease Ron resulting high speed- high frequency device. The seminar was concluded by Dr. Mohammad Abdul Mannan (Associate Professor & Head, Undergraduate Program, Department of EEE) in which he thanked everyone for attending the seminar and also had an interactive question and answer session along with the speaker. The seminar was graced with presence of Mr. Nafiz Ahmed Chisty, (Asssisstant Professor& Special Assisstant, Department of EEE) & Mr. Subrata Biswas(Faculty, Dept. of EEE). Summary of the Seminar Topic: An AlGaN/GaN-based high-electron-mobility transistor (HEMT) is considered as an excellent candidate for future power devices due to its high breakdown voltage, high saturation drain current and low on-resistance (Ron). However, increased dynamic Ron by current collapse is regarded as one of the most critical issues to be solved for actual power-switching applications. Current collapse measurements have been performed for AlGaN/GaN HEMTs having identical breakdown voltages but with different field plate lengths. The results indicated that applying more positive on-state gate biases resulted in pronounced recovery in the dynamic on-resistance for the FP device, whereas no gate-bias effects were observed for the device without FP. The mechanism responsible for the reduced current collapse by FP is proposed, in which the key role is played during on-state by the quick field-effect recovery of partial channel depletion caused by electron trapping at AlGaN surface states between gate and drain.