A novel high-speed broad wavelength InAlAs/InGaAs Schottky barrier photodiode for 0.4 to 1.6 mu m detection

A high-speed, broadband InAlAs/InGaAs graded superlattice Schottky barrier photodiode with useful spectral response extending from 0.4 to 1.6 mu m is demonstrated. The top, wide-bandgap n-In/sub 0.52/Al/sub 0.48/As epilayer absorbs photons in the visible to near-infrared, with peak response occurring around 0.8 mu m; the bottom n-In/sub 0.53/Ga/sub 0.47/As epilayer absorbs photons in the 1.0 to 1.6 mu m wavelength regime, with peak response occurring at 1.3 mu m. The photodiode has a responsivity of 0.34 A/W at 0.8 mu m and 0.42 A/W at 1.3 mu m. Excellent dark I-V characteristics with a reverse leakage current of <1.2 nA and junction capacitance of <0.1 pF at -5 V have been achieved.<>