Electron microscopy characterization of AlGaN/GaN heterostructures grown on Si (111) substrates. (March 2017)

• Record Type: Journal Article
• Authors: Gkanatsiou, A.; Lioutas, Ch. B.; Frangis, N.; Polychroniadis, E.K.; Prystawko, P.; Leszczynski, M.
• Is Part Of: Superlattices and microstructures. Volume 103(2017)
• Page Start: 376
• Page End: 385
• Publication Date: 2017-03
• Subjects: AlGaN/GaN -- Heterostructure -- TEM -- HRTEM -- High electron mobility transistor -- Si substrate; Superlattices as materials -- Periodicals; Microstructure -- Periodicals; Semiconductors -- Periodicals; Superréseaux -- Périodiques; Microstructure (Physique) -- Périodiques; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.spmi.2016.10.024
• Languages: English
• ISSNs: 0749-6036

Abstract

Abstract: AlGaN/GaN buffer heterostructures were grown on "on axis" and 4 deg off Si (111) substrates by MOVPE. The electron microscopy study reveals the very good epitaxial growth of the layers. Almost c-plane orientated nucleation grains are achieved after full AlN layer growth. Step-graded AlGaN layers were introduced, in order to prevent the stress relaxation and to work as a dislocation filter. Thus, a crack-free smooth surface of the final GaN epitaxial layer is achieved in both cases, making the buffer structure ideal for the forthcoming growth of the heterostructure (used for HEMT device applications). Finally, the growth of the AlGaN/GaN heterostructure on top presents characteristic and periodic undulations (V-pits) on the surface, due to strain relaxation reasons. The AlN interlayer grown in between the heterostructure demonstrates an almost homogeneous thickness, probably reinforcing the 2DEG electrical characteristics. Highlights: Structural properties of AlGaN/GaN buffer heterostructures grown on "on axis" and 4 deg off Si (111) substrates are investigated. The introduced step-graded AlGaN layers work as a dislocation filter. Almost c-plane orientated nucleation grains are achieved after full AlN layer growth. A crack free smooth buffer structure surface is achieved, ideal for the forthcoming AlGaN/GaN heterostructure growth.