Waveguide-based type-II heterostructure photodiode on InAs substrate with broad wavelength range photoresponse

Waveguide-based photodiodes with photoresponse in a broad wavelength range are grown on InAs substrates by molecular beam epitaxy. Detection of visible and near-infrared radiation is achieved using a waveguide core formed by a GaSb-pn diode; coupled InAs-GaSb heterostructures forming a superlattice serve as absorption region for mid-infrared radiation. An increase of the photoresponse and detectivity more than one order of magnitude is observed for edge coupling in comparison to nearly perpendicular incidence of the radiation. Room temperature photoresponse is R/sub /spl lambda//=5.32 A/W, detectivity D/sup */=6.0×10/sup 10/ cm/spl middot/Hz
¹
2//W for a wavelength of /spl lambda/=1.064 μm while R/sub /spl lambda//=0.01 A/W and D/sup */=1.0×10/sup 8/ cm/spl middot/Hz
¹
2//W for /spl lambda/=3.062 μm.