AlGaN/GaN HEMTs with very thin buffer on Si (111) for nanosystems applications

Abstract

In the present work, AlGaN/GaN high electron mobility transistors (HEMTs) have been grown with very thin buffer layers on silicon substrates in view of developing nano electromechanical systems (NEMS) for sensors applications. To ensure transducer operation in the MHz range together with low mechanical stiffness, epitaxial structures with thickness below 1 μm have to be developed. We report on the evolution of the material and electrical properties of AlGaN/GaN HEMTs with thicknesses varying from 2 μm to 0.5 μm. The set of parameters obtained includes in-plane Young modulus of 250 GPa in association with carrier density of 6 × 1012 cm−2 and mobility above 1000 cm2 V−1 s−1. The resulting behavior of demonstration transistors validates these epilayers for electromechanical resonators operation.