Picture of virus under microscope

Research under the microscope...

The Strathprints institutional repository is a digital archive of University of Strathclyde research outputs.

Strathprints serves world leading Open Access research by the University of Strathclyde, including research by the Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), where research centres such as the Industrial Biotechnology Innovation Centre (IBioIC), the Cancer Research UK Formulation Unit, SeaBioTech and the Centre for Biophotonics are based.

Explore SIPBS research

Compositional pulling effects in InxGa1-x N/GaN layers: A combined depth-resolved cathodoluminescence and Rutherford backscattering/channeling study

Pereira, S. and Correia, M.R. and Pereira, E. and O'Donnell, K.P. and Trager-Cowan, C. and Sweeney, F. and Alves, E. (2001) Compositional pulling effects in InxGa1-x N/GaN layers: A combined depth-resolved cathodoluminescence and Rutherford backscattering/channeling study. Physical Review B: Condensed Matter and Materials Physics, 64 (205311). pp. 205311-1. ISSN 1098-0121

Full text not available in this repository. (Request a copy from the Strathclyde author)

Abstract

A depth-resolved study of the optical and structural properties of wurtzite InGaN/GaN bilayers grown by metallorganic chemical vapor deposition on sapphire substrates is reported. Depth-resolved cathodoluminescence (CL) and Rutherford backscattering spectrometry (RBS) were used to gain an insight into the compositional profile of a 75-nm thick InGaN epilayer in the direction of growth. CL acquired at increasing electron energies reveals a peak shift of about 25 meV to the blue when the electron beam energy is increased from 0.5 to ~7 keV, and shows a small shift to lower energies between ~7 and 9 keV. For higher accelerating voltages the emission energy peak remains constant. This behavior can be well accounted for by a linear variation of In content over depth. Such an interpretation conforms to the In/Ga profile derived from RBS, where a linear decrease of the In mole fraction from the near surface (~0.20) down to the near GaN/InGaN interface (~0.14) region fits the random spectra very well. Furthermore, by measuring the tetragonal distortion at different depths, using RBS/channeling, it is shown that regions of higher In content also appear to be more relaxed. This result suggests that strain hinders the incorporation of In atoms in the InGaN lattice, and is the driving force for the compositional pulling effect in InGaN films.