Issue 44, 2016

Composition variation in Al-based dilute nitride alloys using apertureless scanning near-field optical microscopy

Abstract

We use apertureless scanning near-field optical microscopy to study the phase separation in chemical beam epitaxy grown Al0.1Ga0.9NxAs1−x alloys. Pits attributed to nitrogen-clustering observed on the Al0.1Ga0.9NxAs1−x surface grown at 420 °C become larger at higher growth temperatures, and 3D islands appear on the surface at 565 °C. Atomic force microscopy phase measurements reveal a composition difference between the islands and the pits, whereas the sample grown at 420 °C appears to be homogeneous. Confocal Raman spectra show that all the N atoms are bonded to Al instead of Ga. Using apertureless scanning near-field optical microscopy, the luminescence of a gold tip is mapped over the surface of the sample grown at 565 °C. We extract the shift of the tip's surface plasmon resonance and determine the variation in the refractive index between the islands and the pits to be close to 0.2. Numerical simulations of the tip luminescence while in contact with the sample predict a similar variation of ∼0.3 in the refractive indices between AlGaAs islands and AlN pits, a substantially smaller value than the difference in the bulk refractive indices of the two media (∼1.8), which we attribute to a convolution of material distribution in an uneven topography. The excellent agreement between simulation and experiments supports the hypothesis of nitrogen-clustering in the pits.

Graphical abstract: Composition variation in Al-based dilute nitride alloys using apertureless scanning near-field optical microscopy

Article information

Article type
Paper
Submitted
20 Jul 2016
Accepted
12 Oct 2016
First published
13 Oct 2016

Phys. Chem. Chem. Phys., 2016,18, 30546-30553

Composition variation in Al-based dilute nitride alloys using apertureless scanning near-field optical microscopy

G. Kolhatkar, A. Boucherif, C. Dab, S. Fafard, V. Aimez, R. Arès and A. Ruediger, Phys. Chem. Chem. Phys., 2016, 18, 30546 DOI: 10.1039/C6CP05063H

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements