Dark current reduction in InGaAs metal-semiconductor-metal photodetectors with coplanar waveguide transmission lines

摘要

InGaAs metal-semiconductor-metal (MSM) photodetectors are one of the promising devices for 1.55 μm lightwave communication systems because of their high-speed performance derived from the low capacitance per unit area. The low dark current and the large signal-to-noise ratio (SNR) are essential for high performance devices. For high-speed application, it is desired to embed MSM photodetector in coplanar wave-guide (CPW) transmission lines. However, one needs to overcome the relative large dark currents resulting from the proximity of the signal line and ground lines. In this study, we describe the effects of etching the epilayers between the signal line and ground lines of a CPW and increasing Schottky barrier enhancement layer thickness on the dark current and gain asymmetry.