Long-wavelength SiGe/Si resonant cavity infrared detector using a bonded silicon-on-oxide reflector

Resonant-enhanced detection of long wavelength infrared radiation using a SiGe/Si multiquantum well device grown on a bonded silicon-on-insulator substrate reflector is reported. A low refractive index in the wavelength region below the 9.2 μm absorption peak in SiO2 gives high Si/SiO2 reflectivities between 7 and 9 μm. Comparison with a control device grown on a p+-Si substrate shows a fivefold enhancement in the peak responsivity at 7.2 μm, which is the resonant wavelength of the cavity formed between the buried Si/SiO2 and the Si/air interfaces.