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In this work, we report on the metal-organic-chemical-vapour-deposition (MOCVD) and characterization of Al-rich thin layers of AlGaN on conductive GaN, to be used as emitter-base barriers for graphene hot electron transistors. After preliminary experiments, aimed to assess the impact of unintentional Ga contaminations on the AlGaN composition, 4.7 nm thick Al0.66Ga0.33N films with a 3 nm GaN cap were deposited on the bulk GaN substrate and, for comparison, on a GaN template on sapphire. XRD measurements were employed to evaluate the composition, thickness and fully strained structure state of the ternary AlGaN barrier layers. Atomic force microscopy (AFM) analyses showed a very smooth surface with atomic steps for the AlGaN barrier layer on the bulk crystal, whereas a rougher surface with high density of pits was observed for the films deposited on the GaN/sapphire sample. Finally a graphene …
Publication date: 
1 Apr 2019

Pawel Prystawko, F Giannazzo, M Krysko, J Smalc-Koziorowska, E Schilirò, G Greco, F Roccaforte, M Leszczynski

Biblio References: 
Volume: 93 Pages: 153-157
Materials Science in Semiconductor Processing