Condensate luminescence under ultraviolet excitation: application to the study of ultrathin SOI layers

We have demonstrated that condensate luminescence is observable in ultrathin silicon-on-insulator (SOI) wafers under ultraviolet (UV) light excitation. The condensation occurred as a result of the shallow penetration depth of the UV light and the confinement effect of photo-excited carriers in a superficial Si layer. The stability of the condensate luminescence overcame the large surface recombination effect inherent in the SOI structure. The spectral shape and temporal decay of the condensate luminescence was shown to be sensitive to crystalline and interfacial defects. We have applied the technique to the characterization of defects in wafers fabricated by the bonding and H+ splitting technique (Unibond® wafers) and analysis of the annealing process in wafers synthesized by separation by implantation oxygen (SIMOX).