Gao F, Chen D, Lu B, et al. Impact of moisture and fluorocarbon passivation on the current collapse of AlGaN/GaN HEMTs[J]. IEEE electron device letters, 2012, 33(10): 1378-1380.
ABSTRACT
In this letter, ambient moisture has been identi-fied as a previously unrecognized cause of current collapse inAlGaN/GaN high-electron-mobility transistors. Unpassivated de-vices exposed to dry air or protected with a hydrophobic passi-vation, such as vapor-deposited fluorocarbon, showed negligiblecurrent collapse under 250-ns pulsed measurements. A mechanismbased on the ionization and deionization of the water molecules atthe device surface has been proposed to explain this behavior. Theuse of a hydrophobic passivation to prevent dc-to-RF dispersionworks even when it is not directly in contact with the semiconduc-tor surface, which allows the engineering of multistack passivationlayers to eliminate current collapse while minimizing parasiticcapacitance.
