Impact of Al₂O₃ Passivation on AlGaN/GaN Nanoribbon High-Electron-Mobility Transistors

Abstract

Passivation films are used in III-nitride (III-N) based devices to suppress current collapse and improve frequency performance. Several passivation films and deposition methods have the added effects of increasing the dc ON-and OFF-state currents in devices. In this paper, the physical mechanisms behind this current increase have been studied in both nanoribbon and planar devices with atomic-layer deposited Al 2 O 3 passivation. Increased tensile stress in the AlGaN layer due to passivation leads to an increase in the charge density in nanoribbon devices. Simultaneously, the mobility in nanoribbons increases after Al 2 O 3 passivation. These effects lead to a large (∼118%) increase in the saturation drain current in nanoribbon devices. In contrast, fixed positive charge at the Al 2 O 3 -AlGaN interface leads to a small (∼6%) saturation drain current increase in planar devices. In addition, the mechanisms behind the increase in the OFFstate drain current in the passivated devices are investigated. Schottky barrier lowering and the increase in surface and buffer conduction are found to be the major causes for the OFF-state current increase with passivation.

Catalyst‐Free Growth of Atomically Thin Bi2O2Se Nanoribbons for High‐Performance Electronics and Optoelectronics

“…Table 1 benchmarks the typical research on nanoribbon designed by various synthesis techniques, materials, and electrical performance. We summarized some well‐known research on nanoribbon‐based FET such as n‐type TMDCs, including MoS 2 , [ 16 ] CdSe, [ 17 ] tri‐chalcogenides TiS 3 , [ 18 ] p‐type graphene nanoribbon, [ 19 ] superlattices of AlGaN/GaN, [ 20 ] and a III–V compound like boron nitride. [ 21 ] The FET based on Bi 2 O 2 Se nanoribbons not only achieves high field‐effect mobility in comparison with graphene nanoribbon but also simplifies the assembly complexity required for the opening of graphene bandgap.…”

High Mobility Anisotropic Black Phosphorus Nanoribbon Field‐Effect Transistor

“…Figure d benchmarks the state‐of‐the‐art research on nanoribbon formed using different materials, synthesis techniques, and electrical performance (see Section S5, Supporting Information). We summarize some prominent work on nanoribbon field‐effect transistor including p‐type graphene nanoribbon, n‐type transition metal dichalcogenides (TMDs) such as MoS 2 , CdSe, CdS, tri‐chalcogenides TiS 3 , III–V compound like boron nitride, and even superlattice such as AlGaN/GaN heterojunctions . Compared with graphene nanoribbon, the BPNR‐FET achieves a high hole mobility at the same time simplifies the fabrication complexity needed to open up the bandgap in graphene.…”

An Overview on Analyses and Suppression Methods of Trapping Effects in AlGaN/GaN HEMTs

“…Furthermore, several novel passivation materials are adopted like MgO [90], ScO 3 [90], [91], Al 2 O 3 [92], AlN [93], MgF 2 [94], TiO 2 [95]. Recently, Koehler et al [93] formed a high crystallinity AlN passivation by atomic layer epitaxy.…”