A new grating-type gold-n-type silicon Schottky-barrier photodiode

The new grating-type Au-n-type Si Schottky-barrier photodiode has been fabricated and analyzed. The device is constructed with a new structure of contact mask. The mask forms a grating of gold film over the contacting silicon substrate. The grating spacing is so chosen that even at zero bias the interfacial layer between the silicon substrate and the gold gratings is completely depleted. The device is fabricated on an n-type silicon wafer of ∼1300-Ω.cm resistivity, and the grating spacing is 12.5 µm. An analysis is performed to determine the I-V characteristics, the spectral dependence of the quantum yield, the responsivity, and the noise characteristics of the photodiode. It is found that without optimization the device has a bandwidth of ∼1 GHz and responsivity of 0.63 A/W at λ =0.9 µm.