Silicon-on-insulator (SOI) wafers were characterized by photoluminescence (PL) under Ultraviolet (UV) light excitation. The shallow penetration depth of the UV light and the confinement effect of photo-excited carriers in the SOI structure enabled us to observe a characteristic condensate luminescence from a Superficial Si layer. The spectrum and decay time of the condensate luminescence was shown to be sensitive to the crystalline and interfacial defects. Combining this luminescence with the PL under visible and near infrared light excitation on both the front and back sides of the wafers allowed us to characterize the quality of the Superficial Si layer, surface/interface and substrate of the SOI wafers. (C) 2002 Elsevier Science B.V. All rights reserved.