Journal of Crystal Growth 230 (2001) 473–476 Photoluminescence of InGaN/GaN multiple quantum wells grown by mass transport G. Pozina a, *, J.P. Bergman a , B. Monemar a ,M.Iwaya b ,S.Nitta b , H. Amano b , I. Akasaki b a Department of Physics and Measurement Technology, Link . oping University, S-581 83 Link . oping, Sweden b Department of Electrical Engineering and Electronics and High-Tech Research Center, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468-8502, Japan Abstract We report on studies of an In 0.12 Ga 0.88 N/GaN structure with three 35 ( A thick quantum wells (QWs) grown by metalorganic vapor phase epitaxy with employment of mass transport. The mass-transport regions demonstrate a threading dislocation density less than 10 7 cm À2 . The photoluminescence (PL) spectrum is dominated by a 40meV}narrow line centered at 2.97eV at 2K. This emission has a typical PL decay time of about 5ns at 2K withinthePLcontour.Anadditionallinewithlongerdecaytime(about200ns)isobservedatanenergyabout2.85eV. Thepositionofthislineshiftstowardshigherenergieswithincreasingexcitationpower.Thedataareconsistentwitha model, where the PL originates from at least two nonequivalent QWs, which could be realized due to a potential gradient across the layers. # 2001 Elsevier Science B.V. All rights reserved. PACS: 78.66.Fd; 78.55.Cr; 78.47.+p; 78.20.Àe Keywords: A3. Quantum wells; B1. Nitrides; B2. Semiconducting III–V materials; B3. Light emitting diodes 1. Introduction The recent demonstration of highly efficient nitride-based blue and green light emitting diodes andvioletlaserdiodes[1,2]stimulatessignificantly further activity in growth and research on hetero- structures based on GaN and nitrides alloys such asInGaN.Furtherdevicedevelopmentdemandsa higher structural quality of the material. It is also important to understand the recombination me- chanisms in such structures. However, the physics ofInGaN/GaNMQWsisstillfarfromacomplete understanding.Thepreviousstudieshaverevealed a variety of optical properties as well as different interpretations. In this work, we report on the optical properties of a high quality InGaN/GaN MQW structure grown by metalorganic vapor phase epitaxy (MOVPE) utilizing the mass trans- port overgrowth technique [3,4]. 2. Experimental procedure A nominally undoped GaN layer of thickness 7 mmwasgrownbyMOVPEona(0001)sapphire *Corresponding author. Tel.: +46-13-28-4479; fax: +46-13- 14-2337. E-mail address: galia@ifm.liu.se (G. Pozina). 0022-0248/01/$-see front matter # 2001 Elsevier Science B.V. All rights reserved. PII:S0022-0248(01)01257-X