title: Near-surface processing on AlGaN/GaN heterostructures: a nanoscale electrical and structural characterization.
abstract: The effects of near-surface processing on the properties of AlGaN/GaN heterostructures were studied, combining conventional electrical characterization on high-electron mobility transistors (HEMTs), with advanced characterization techniques with nanometer scale resolution, i.e., transmission electron microscopy, atomic force microscopy (AFM) and conductive atomic force microscopy (C-AFM). In particular, a CHF3-based plasma process in the gate region resulted in a shift of the threshold voltage in HEMT devices towards less negative values. Two-dimensional current maps acquired by C-AFM on the sample surface allowed us to monitor the local electrical modifications induced by the plasma fluorine incorporated in the material.The results are compared with a recently introduced gate control processing: the local rapid thermal oxidation process of the AlGaN layer. By this process, a controlled thin oxide layer on surface of AlGaN can be reliably introduced while the resistance of the layer below increase locally.
authors.affiliation: Consiglio Nazionale delle Ricerche - Istituto per la Microelettronica e Microsistemi (CNR-IMM), Strada VIII n, 5, Zona Industriale, 95121 Catania, Italy. fabrizio.roccaforte@imm.cnr.it.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Greco
authors.forename: Filippo
authors.initials: F
authors.lastname: Giannazzo
authors.forename: Alessia
authors.initials: A
authors.lastname: Frazzetto
authors.forename: Vito
authors.initials: V
authors.lastname: Raineri
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Roccaforte