Wavelength dependent characteristics of high-speed metamorphic photodiodes

Double-heterojunction photodiodes based on GaAs metamorphic growth technology are described. The effect of the large bandgap InAlAs layer incorporated in the device heterostructure was examined by measuring wavelength dependent responsivities and bandwidths at 0.85-, 1.33-, and 1.55(mu)m illumination. The photodiodes exhibited 0.4 A/W responsivity and over 50-GHz bandwidth for 1.55-(mu)m laser illumination. The bias voltage required to achieve the maximum bandwidth was measured to be less than -1 V.