The suspended SU-8 waveguide MSM-photodetector for visible light directly based on silicon substrate

The suspended waveguide MSM (metal-semiconductor-metal)-photodetector for visible light is designed and fabricated directly based on silicon substrate due to the fact that the SU-8 ridge waveguide has a low absorption loss and the silicon can work as active material during visible light range. An intermediate layer between waveguide and silicon has been adopted to protect the electrode during wet etching. Through the selection of more appropriate intermediate layer material and the improved fabrication process, the length of electrode decreases from 710 µm to 150 µm and the dark current is reduced from 4.39 uA@5V to 200 nA@2.5 V, meanwhile the responsibility is improved from 0.232A/W@5V to 0.326 A/W@2.5 V.