title: Nanoscale conductive pattern of the homoepitaxial AlGaN/GaN transistor.
abstract: The gallium nitride (GaN)-based buffer/barrier mode of growth and morphology, the transistor electrical response (25-310 °C) and the nanoscale pattern of a homoepitaxial AlGaN/GaN high electron mobility transistor (HEMT) have been investigated at the micro and nanoscale. The low channel sheet resistance and the enhanced heat dissipation allow a highly conductive HEMT transistor (Ids > 1 A mm(-1)) to be defined (0.5 A mm(-1) at 300 °C). The vertical breakdown voltage has been determined to be ∼850 V with the vertical drain-bulk (or gate-bulk) current following the hopping mechanism, with an activation energy of 350 meV. The conductive atomic force microscopy nanoscale current pattern does not unequivocally follow the molecular beam epitaxy AlGaN/GaN morphology but it suggests that the FS-GaN substrate presents a series of preferential conductive spots (conductive patches). Both the estimated patches density and the apparent random distribution appear to correlate with the edge-pit dislocations observed via cathodoluminescence. The sub-surface edge-pit dislocations originating in the FS-GaN substrate result in barrier height inhomogeneity within the HEMT Schottky gate producing a subthreshold current.
authors.affiliation: The Catalan Institute of Nanoscience and Nanotechnology (ICN2), E-08193 Barcelona, CAT, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Pérez-Tomás
authors.forename: G
authors.initials: G
authors.lastname: Catalàn
authors.forename: A
authors.initials: A
authors.lastname: Fontserè
authors.forename: V
authors.initials: V
authors.lastname: Iglesias
authors.forename: H
authors.initials: H
authors.lastname: Chen
authors.forename: P M
authors.initials: PM
authors.lastname: Gammon
authors.forename: M R
authors.initials: MR
authors.lastname: Jennings
authors.forename: M
authors.initials: M
authors.lastname: Thomas
authors.forename: C A
authors.initials: CA
authors.lastname: Fisher
authors.forename: Y K
authors.initials: YK
authors.lastname: Sharma
authors.forename: M
authors.initials: M
authors.lastname: Placidi
authors.forename: M
authors.initials: M
authors.lastname: Chmielowska
authors.forename: S
authors.initials: S
authors.lastname: Chenot
authors.forename: M
authors.initials: M
authors.lastname: Porti
authors.forename: M
authors.initials: M
authors.lastname: Nafría
authors.forename: Y
authors.initials: Y
authors.lastname: Cordier