Core–shell InGaN/GaN nanowire light emitting diodes analyzed by electron beam induced current microscopy and cathodoluminescence mapping

M. Tchernycheva; V. Neplokh; H. Zhang; P. Lavenus; L. Rigutti; F. Bayle; F. H. Julien; A. Babichev; G. Jacopin; L. Largeau; R. Ciechonski; G. Vescovi; O. Kryliouk

doi:10.1039/C5NR00623F

Core–shell InGaN/GaN nanowire light emitting diodes analyzed by electron beam induced current microscopy and cathodoluminescence mapping†

M. Tchernycheva,*^a V. Neplokh,^a H. Zhang,^a P. Lavenus,^a L. Rigutti,^ab F. Bayle,^a F. H. Julien,^a A. Babichev,^acd G. Jacopin,^e L. Largeau,^f R. Ciechonski,^g G. Vescovi^g and O. Kryliouk^h

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* Corresponding authors

^a Institut d'Electronique Fondamentale, UMR 8622 CNRS, University Paris Sud, 91405 Orsay cedex, France
E-mail: maria.tchernycheva@u-psud.fr

^b Groupe de Physique des Matériaux, UMR CNRS 6634, University and INSA of Rouen, Normandie University, 76800 St. Etienne du Rouvray, France

^c ITMO University, 197101 St. Petersburg, Russia

^d Ioffe Institute, 194021 St. Petersburg, Russia

^e ICMP LOEQ Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

^f LPN-CNRS, Route de Nozay, 91460 Marcoussis, France

^g GLO AB, Ideon Science Park, Scheelevägen 17, S-223 70 Lund, Sweden

^h GLO-USA, 1225 Bordeaux Dr, Sunnyvale, CA, USA

Abstract

We report on the electron beam induced current (EBIC) microscopy and cathodoluminescence (CL) characterization correlated with compositional analysis of light emitting diodes based on core/shell InGaN/GaN nanowire arrays. The EBIC mapping of cleaved fully operational devices allows to probe the electrical properties of the active region with a nanoscale resolution. In particular, the electrical activity of the p–n junction on the m-planes and on the semi-polar planes of individual nanowires is assessed in top view and cross-sectional geometries. The EBIC maps combined with CL characterization demonstrate the impact of the compositional gradients along the wire axis on the electrical and optical signals: the reduction of the EBIC signal toward the nanowire top is accompanied by an increase of the CL intensity. This effect is interpreted as a consequence of the In and Al gradients in the quantum well and in the electron blocking layer, which influence the carrier extraction efficiency. The interface between the nanowire core and the radially grown layer is shown to produce in some cases a transitory EBIC signal. This observation is explained by the presence of charged traps at this interface, which can be saturated by electron irradiation.

Nanoscale

Core–shell InGaN/GaN nanowire light emitting diodes analyzed by electron beam induced current microscopy and cathodoluminescence mapping†

Abstract

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Core–shell InGaN/GaN nanowire light emitting diodes analyzed by electron beam induced current microscopy and cathodoluminescence mapping

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