Issue 20, 2012
From the journal:

Nanoscale

Nanowires as semi-rigid substrates for growth of thick, InxGa1−xN (x > 0.4) epi-layers without phase segregation for photoelectrochemical water splitting†

Chandrashekhar Pendyala,a   Jacek B. Jasinski,b   Jeong H. Kim,a   Venkat Kalyan Vendra,a   Sergey Lisenkov,c   Madhu Menond  and  Mahendra K. Sunkara*ab  

* Corresponding authors

a Department of Chemical Engineering, University of Louisville, Louisville, KY 40292, USA
E-mail: mahendra@louisville.edu

b Conn Center for Renewable Energy Research, University of Louisville, Louisville, KY 40292, USA

c Department of Physics, University of South Florida, Tampa, FL 33620-5700, USA

d Department of Physics and Astronomy and Center for Computational Sciences, University of Kentucky, Lexington, KY 40506, USA

Abstract

Here, we show that GaN nanowires (diameter <30 nm) can be used as strain relaxing substrates for the heteroepitaxial growth of stable InxGa1−xN alloys of controlled composition and thickness. Thinner nanowires with their smaller interfacial area reduce the heteroepitaxial stress. Also, the limited adatom diffusion length scales on the thinner nanowires aid in reducing the kinetic segregation effects. In addition to being single crystal templates for heteroepitaxial growth, these thick single crystal overlayers on nanowire substrates can provide suitable architectures for photoelectrochemical applications. The stability and crystallinity of the InxGa1−xN layers are preserved by the nanowires acting as compliant substrates. Photoelectrochemical water splitting requires InxGa1−xN alloys with a 2.2–1.6 eV band gap (i.e. 0.45 < x < 0.65) and 150–200 nm film thickness for efficient light absorption and carrier generation. At such compositions, the InxGa1−xN alloys are inherently unstable, the thickness-dependent stress builds up during the commonly employed heteroepitaxial growth methods, and adds to the instability causing phase segregation and property degradation. A dependence of the growth morphology on the GaN nanowire growth orientation was observed and a growth mechanism is presented for the observed orientation dependent growth on a-plane and c-plane GaN nanowires. Photoactivity of GaN and InxGa1−xN films on GaN nanowires is also investigated which shows a distinct difference attributable to GaN and InxGa1−xN, demonstrating the advantages of using nanowires as strain relaxing substrates.

Graphical abstract: Nanowires as semi-rigid substrates for growth of thick, InxGa1−xN (x > 0.4) epi-layers without phase segregation for photoelectrochemical water splitting

About
Cited by
Related
Download options Please wait...

Supplementary files

Article information

DOI
https://doi.org/10.1039/C2NR32020G
Article type
Communication
Submitted
11 Jun 2012
Accepted
18 Aug 2012
First published
20 Aug 2012

Nanoscale, 2012,4, 6269-6275

Permissions

Request permissions

Nanowires as semi-rigid substrates for growth of thick, InxGa1−xN (x > 0.4) epi-layers without phase segregation for photoelectrochemical water splitting

C. Pendyala, J. B. Jasinski, J. H. Kim, V. K. Vendra, S. Lisenkov, M. Menon and M. K. Sunkara, Nanoscale, 2012, 4, 6269 DOI: 10.1039/C2NR32020G

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