Cathodoluminescence microanalysis of porous GaP and InP structures

¹ Laboratory of Low-Dimensional Semiconductor Structures, Institute of Applied Physics, Technical University of Moldova, MD-2004 Chisinau, Moldova
² Department of Materials Science, Faculty of Engineering, Christian-Albrechts University,Keiserstr. 2, D-24143 Kiel, Germany
³ School of Physics, University of NSW Sydney, NSW 2052, Australia

Corresponding author: tiginyan@mail.utm.md

Received: 25 September 2003
Accepted: 28 January 2004
Published online: 15 July 2004

Abstract

Electron microscopy and cathodoluminescence (CL) microanalysis were used for a comparative study of porous layers fabricated by electrochemical etching of n-GaP and n-InP substrates in aqueous solutions of sulfuric and hydrochloric acids. Both the CL and morphology of porous layers were found to depend upon the anodic current density. At high current density (100 mA/cm²) anodization leads to the formation of so-called current-line oriented pores while at low current densities the pores grow along crystallographic directions. The porosity relief was found to give rise to spatial modulation of the CL intensity. The composition microanalysis proved the stoichiometry of porous GaP and InP skeletons, although we found considerable traces of oxygen in porous GaP layers. Self-induced voltage oscillations giving rise to a synchronous modulation of the diameter of pores and CL intensity were evidenced.