Pulsed current-voltage characteristics of AlGaN/GaN high-electron-mobility-transistors on HR-Si substrate

• Main Author: Lee, Wei Yi.
• Other Authors: Ng Geok Ing
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Semiconductors
• Online Access: http://hdl.handle.net/10356/17756
• Institution: Nanyang Technological University

In recent years, much research has been carried out on AlGaN/GaN high-electron-mobility transistors (HEMTs) on high resistivity (HR) silicon substrate. AlGaN/GaN HEMT is popular for its advantages for high-power and high-frequency applications. Though AlGaN/GaN HEMT showed high power performance [3], still the devices are suffering from drain current collapse [4]. To evaluate the current collapse, pulsed current-voltage measurement is an effective tool. In this project, the pulsed current-voltage characteristics of the device have been investigated. Devices of different gate-drain lengths, LGD were used. Literature reviews on HEMT’s device structure and characteristics were first carried out to have a clear understanding on the necessary theories and knowledge required. This made analysis on the results much easier later. Three types of measurements were performed – static (DC) IDS-VDS, pulsed IDS-VDS and transient current characteristics. The decrease of drain current with the increase of drain voltage is due to the effect of device self-heating. The main investigation of this project was to observe the drain current collapse under different conditions including the quiescent bias points, pulse width, pulse period and the transient current response. Results showed that the current collapse, ID generally suffered the most severe when bias stress was applied at the gate-source and gate-drain regions. The AlGaN/GaN HEMT devices are dominantly affected by either the barrier- or the buffer-related traps. The time constant for the dispersion effect was found to be relatively long. The trapping process was found to be 10 s at transient response. Moreover, the steady-state conditions are differing for different bias conditions Lastly, this report has summarised all the results analysed and recommended the possible approaches for future investigations in this project.