Dark current suppression in an erbium–germanium–erbium photodetector with an asymmetric electrode area

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In this work, suppression of the dark current level in a metal-semiconductor-metal (MSM) photodetector fabricated on the intrinsic (i) Ge is achieved by exploiting (1) the Er electrode, providing a relatively high hole barrier, and (2) the concept of asymmetric electrode area, to minimize the Schottky barrier height lowering effect. Compared with a symmetric MSM photodetector fabricated with Ti electrodes, the dark current level was reduced by a factor of about 80. This low dark current i-Ge MSM photodetector is promising for applications requiring low power and a high photo-to-dark-current ratio.