Towards the ultimate goal of AlN-based HEMTs grown on silicon substrates

Description

Using NH3-MBE, AlN-based HEMTs on silicon are demonstrated for the first time. Ultra-thin heterostructures typically consist of 200 nm-thick AlN buffer, followed by 20 nm-thick strained GaN channel, 3-10 nm-thick AlN barrier. 2DEG densities (Ns) are measured as a function of AlN barrier thicknesses. Value as high as 2.7x10 13 cm-2 is measured before passivation. Ns increases improving the material quality and using SiN passivation. In-situ SiN passivation using NH3-MBE is presented for the first time. State-of-the-art mobility values above 600 cm²/Vs are measured and recent improvements are ongoing to lower the sheet resistance as required for high-frequency applications.

Abstract

International audience

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