Electron accumulation at InN/AlN and InN/GaN interfaces

Abstract

The electron accumulation at InN/AlN and InN/GaN interfaces is investigated in InN epilayers grown by molecular beam epitaxy. Hall measurements as a function of InN film thickness are used to determine the excess sheet density that results from both surface and interface charge accumulation. Using high-resolution electron-energy-loss spectroscopy (HREELS), the surface sheet density is found to be the same for InN films grown on both AlN and GaN buffer layers. The combination of the Hall and HREELS results indicates that the sheet density associated with the charge accumulation at the InN/buffer layer interface is significantly higher for AlN buffers (1.9 × 1013 cm–2) than for GaN buffers (<0.5 × 1013 cm–2). This buffer layerdependence of the interface accumulation is discussed in terms of lattice mismatch and the effect of mixed polarity on the spontaneous polarization. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)