The Si metal-oxide-semiconductor structure can be used for light detection, and the dark current is significantly reduced
with the oxide layer. With the photo excitation, the generated carriers can be collected by electrodes as photo current. By
incorporating Ge, the metal-oxide-semiconductor photodetectors can increase the responsivity and extend the detection
wavelength. The interband transitions in the SiGe quantum dots enhance the 820 nm infrared absorption and extend the
detection range to 1550nm. The valence band offset between Si and SiGe forms discrete quantum states in the SiGe
layers. Hence, metal-oxide-semiconductor SiGe/Si quantum dot (well) infrared photodetectors can be used to detect midand
far- infrared using the intraband transitions. The Ge-on-insulator metal-oxide-semiconductor photodetectors can
further increase the detection speed by reducing parasitic capacitance. The large work function metal (Pt) is used for the
gate electrode to reduce the dark current. Moreover, the external mechanical strain can enhance the photo current with
slight degradation of dark current.
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