Brief Note Defect distribution in InGaAsN/GaAs multilayer solar cells A. Kosa a,⇑ , L. Stuchlikova a , L. Harmatha a , M. Mikolasek a , J. Kovac a , B. Sciana b , W. Dawidowski b , D. Radziewicz b , M. Tlaczala b a Institute of Electronics and Photonics, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Bratislava 81219, Slovakia b Division of Microelectronics and Nanotechnology, Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Wroclaw 50372, Poland Received 7 December 2015; received in revised form 3 March 2016; accepted 17 March 2016 Available online 11 April 2016 Communicated by: Associate Editor Bibek Bandyopadhyay Abstract Deep Level Transient Fourier Spectroscopy (DLTFS) experiments were realized to study emission and capture processes in InGaAsN multilayer solar cells grown on GaAs substrates by Atmospheric Pressure Metal Organic Vapor Phase Epitaxy (APMOVPE). As a referent structure for comparison purposes a basic GaAs p–n sample grown in the same system was also utilized. All the structures exhibited variety of deep energy levels with high concentrations. In addition to the most commonly described arsenic antisite defect, with activation energies 0.73–0.78 eV, possible traces of oxygen–arsenic vacancies with 0.52 eV and nitrogen interstitial complexes were evaluated. Most dominant electron trap at about 0.53 eV below the conduction band E C was observed at different measurement conditions. Based on various references, this electron trap can be associated with a split interstitial defect containing two nitrogen atoms on the same As lattice site. Calculated energies and possible origins of these results were confirmed by Arrhenius curve comparison. Ó 2016 Elsevier Ltd. All rights reserved. Keywords: Deep Level Transient Fourier Spectroscopy; InGaAsN/GaAs; Tandem solar cell; Semiconductor defect Solar energy is one of the many energy forms harnessed by humanity in order to produce electricity in an environmental friendly and efficient way. Today it is reli- able, long-lasting and pollution free alternative of electric- ity generation, which has rapidly grown with high importance in the last decade (Lee et al., 2015). In order to maintain reliability and low cost not only the market leading silicon solar cells , but also novel materials such as organic or hybrid organic–inorganic materials are exten- sively studied (Bella, 2015a, 2015b). III–V compound based multi-junction solar cells have the potential for achieving high conversion efficiencies and are promising for space and terrestrial applications (Yamaguchi et al., 2005, 2008). Dilute-nitride InGaAsN based solar cells lattice matched to GaAs were demonstrated as working prototypes since 1998 (Friedman et al., 1998). Sub cells with adequate performances for 3 junction cells were reported in 2007 (Jackrel et al., 2006). World record efficiency 43.5% has been achieved by multijunction solar cells employing GaInNAsSb junctions (Sabnis et al., 2012; Kim et al., 2014). New approaches for InGaAsN based structures are continuously studied to realize 50% efficiency by 4- or 5-junction solar cells lattice matched to GaAs and Ge substrates (Yamaguchi et al., 2012a). Application of this promising material however requires the understanding of electrically active defect generation and effects on device performance. Investigation must be http://dx.doi.org/10.1016/j.solener.2016.03.057 0038-092X/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: arpad.kosa@stuba.sk (A. Kosa). www.elsevier.com/locate/solener Available online at www.sciencedirect.com ScienceDirect Solar Energy 132 (2016) 587–590