Available online at www.sciencedirect.com Physica E 17 (2003) 250–251 www.elsevier.com/locate/physe Photo-induced transient spectroscopy and in-plane photovoltage in GaInNAs/GaAs quantum wells S. Mazzucato a , A. Erol b , A. Teke c , M.C. Arikan b , R.J. Potter a , N. Balkan a ; * , X. Marie d , A. Boland-Thoms a ,H.Carr ere e , E. Bedel e , G. Lacoste e , C. Fontaine e , A. Arnoult e a Photonics Group, Department of ESE, University of Essex, CO4 3SQ Colchester, UK b Department of Physics, Istanbul University, Vezneciler, Istanbul, Turkey c Department of Physics, Balikesir University, Balikesir, Turkey d Laboratoire de Physique de la Mati ere Condens ee (CNRS UMR 5830), INSA - D ept. de Physique, 31077 Toulouse Cedex, France e Laboratoire d’Analyse et d’Architecture des Syst emes (LAAS - CNRS), 7 avenue du Colonel Roche, 31077 Toulouse Cedex 4, France Abstract We have studied the optical quality of sequentially grown undoped Ga0:8In0:2As and Ga0:8In0:2N0:015As0:985 quantum wells (QWs). Spectral and time-resolved in-plane photovoltage (IPV) and photo-induced transient spectroscopy (PITS) techniques were used in this investigation. Two clear peaks have been observed and analysed in the PITS experiment. Spectral and transient IPV in the same samples has been investigated and a selective light was used as the excitation source to separate the GaInNAs IPV from the other layers. IPV can be explained in terms of random uctuations of the Fermi level in undoped QWs. Spectral and time-resolved IPV measurements can therefore be used to obtain qualitative and quantitative information about interband transitions and trap activation energies. ? 2002 Elsevier Science B.V. All rights reserved. PACS: 71.55.Eq; 73.50.Pz; 73.20.Hb Keywords: GaInNAs; In-plane photovoltage; PITS; Fermi level uctuation 1. Introduction The quaternary alloy GaInNAs promises to be an ideal material system for many applications in opto- electronics. The diculty of incorporating nitrogen in GaInAs has provoked much work to understand the factors aecting the optical quality, such as composi- tion, growth and annealing conditions [1]. * Corresponding author. Tel.: +44-1206-872878; fax: +44-1206- 873598. E-mail address: balkan@essex.ac.uk (N. Balkan). In this work, we used two dierent techniques to investigate the presence of defects and traps in ni- trogen free and nitrogen containing quantum wells (QWs). 2. Results and discussion The sample studied was grown using molecular beam epitaxy [2] and fabricated in form of single bar with a 1 mm 2 optical window where the excit- ing light was incident on. The structure contains two undoped 9 nm QWs, one Ga 0:8 In 0:2 As and the other 1386-9477/03/$ - see front matter ? 2002 Elsevier Science B.V. All rights reserved. doi:10.1016/S1386-9477(02)00786-5