Integration of Si p-i-n diodes for light emitter and detector with optical waveguides

Si p-i-n diodes for light emitters and detectors with optical waveguides have been integrated on silicon-on-insulator (SOI) substrates, and photo detection from the light emitter has been investigated. It is found that photodiode (PD) current at reverse bias is well normalized by the light-emitting diode (LED) current at forward bias. From the comparison between PD characteristics with and without optical waveguide, it is confirmed that increase of the PD current is mainly caused by light incidence, not by thermal effect due to LED heating. This means that the PD current is generated by higher energy photons than the energy bandgap of Si. Therefore, it is concluded that, even for the same structures of PD as LED of Si p-i-n, light emitted from LED is detected by PD.