Metal organic vapour phase epitaxy (MOVPE)-grown InGaAs quantum wells (QWs) with low and high built-in strain are investigated by using complementary spectroscopic techniques like photoluminescence (PL) and surface photovoltage spectroscopy (SPS). The built-in strain is varied by increasing the indium content while keeping the QW thickness constant. An extreme case of high built-in strain of ultrathin InAs QW is also discussed and useful information has been obtained from SPS technique at room temperature itself where no PL signal was seen due to either presence of high defect/dislocation density or thermal escape of charge carriers in case of a shallow QW. (c) 2006 Elsevier B.V. All rights reserved.