The impact of surface states on the DC and RF characteristics of AlGaN/GaN HFETs
Top Cited Papers
- 1 March 2001
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Electron Devices
- Vol. 48 (3) , 560-566
- https://doi.org/10.1109/16.906451
Abstract
GaN based HFETs are of tremendous interest in applications requiring high power at microwave frequencies. Although excellent current-voltage (I-V) characteristics and record high output power densities at microwave frequencies have been achieved, the origin of the 2DEG and the factors limiting the output power and reliability of the devices under high power operation remain uncertain. Drain current collapse has been the major obstacle in the development of reliable high power devices. We show that the cause of current collapse is a charging up of a second virtual gate, physically located in the gate drain access region. Due to the large bias voltages present on the device during a microwave power measurement, surface states in the vicinity of the gate trap electrons, thus acting as a negatively charged virtual gate. The maximum current available from a device during a microwave power measurement is limited by the discharging of this virtual gate. Passivated devices located adjacent to unpassivated devices on the same wafer show almost no current collapse, thus demonstrating that proper surface passivation prevents the formation of the virtual gate. The possible mechanisms by which a surface passivant reduces current collapse and the factors affecting reliability and stability of such a passivant are discussed.Keywords
This publication has 13 references indexed in Scilit:
- High Al-content AlGaN/GaN HEMTs on SiC substrates with very high power performancePublished by Institute of Electrical and Electronics Engineers (IEEE) ,2003
- Gallium nitride based high power heterojunction field effect transistors: process development and present status at UCSBIEEE Transactions on Electron Devices, 2001
- Polarization effects, surface states, and the source of electrons in AlGaN/GaN heterostructure field effect transistorsApplied Physics Letters, 2000
- The effect of surface passivation on the microwave characteristics of undoped AlGaN/GaN HEMTsIEEE Electron Device Letters, 2000
- Polarization induced 2DEG in MBE grown AlGaN/GaN HFETs: On the origin, DC and RF characterizationMRS Proceedings, 2000
- Results, Potential and Challenges of High Power GaN-Based TransistorsPhysica Status Solidi (a), 1999
- Polarization-induced charge and electron mobility in AlGaN/GaN heterostructures grown by plasma-assisted molecular-beam epitaxyJournal of Applied Physics, 1999
- Drain current compression in GaN MODFETs underlarge-signalmodulation at microwave frequenciesElectronics Letters, 1999
- Large signal frequency dispersion of AlGaN/GaNheterostructure fieldeffect transistorsElectronics Letters, 1999
- Two-dimensional electron gases induced by spontaneous and piezoelectric polarization charges in N- and Ga-face AlGaN/GaN heterostructuresJournal of Applied Physics, 1999