Characterization of silicon-on-insulator wafers by photoluminescence decay lifetime measurement

The lifetime of an electron-hole droplet (EHD) generated in a superficial Si layer of a silicon-on-insulator (SOI) wafer was investigated using time-resolved photoluminescence technique. Formation of the EHD in the superficial Si layer was realized employing pulsed ultraviolet laser light as an excitation source, because of its shallow penetration depth and confinement of photo-excited carriers in the layer. Dependence of the EHD lifetime on surface condition, fabrication technique and wafer vendor was successfully observed. We demonstrated that the EHD lifetime is sensitive to crystalline quality of the superficial Si layer, and propose that the present method has great potential for characterization of SOI wafers.