title: Nanoscale electrical and structural modification induced by rapid thermal oxidation of AlGaN/GaN heterostructures.
abstract: In this paper, the structural and electrical modifications induced, in the nanoscale, by a rapid thermal oxidation process on AlGaN/GaN heterostructures, are investigated. A local rapid oxidation (900 ° C in O2, 10 min) localized under the anode region of an AlGaN/GaN diode enabled a reduction of the leakage current with respect to a standard Schottky contact. The insulating properties of the near-surface oxidized layer were probed by a nanoscale electrical characterization using scanning probe microscopy techniques. The structural characterization indicated the formation of a thin uniform oxide layer on the surface, with preferential oxidation paths along V-shaped defects penetrating through the AlGaN/GaN interface. The oxidation process resulted in an expansion of the lattice parameters due to the incorporation of oxygen atoms, accompanied by an increase of the crystal mosaicity. As a consequence, a decrease of the sheet carrier density of the two-dimensional electron gas and a positive shift of the threshold voltage are observed. The results provide useful insights for a possible future integration of rapid oxidation processes during GaN device fabrication.
authors: Consiglio Nazionale delle Ricerche-Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII 5, Zona Industriale-I-95121 Catania, Italy.
authors: Giuseppe
authors: G
authors: Greco
authors: Patrick
authors: P
authors: Fiorenza
authors: Filippo
authors: F
authors: Giannazzo
authors: Alessandra
authors: A
authors: Alberti
authors: Fabrizio
authors: F
authors: Roccaforte