This paper discusses the influence of Si3N4 barrier layer on photoelectric properties of black silicon photodetector.A barrier layer is added between the black silicon layer and the electrode in the metal-semiconductor-metal(MSM) structure in order to increase the Schottky barrier,leading to the decrease of the dark current.According to the experiment,under the same lighting condition,the dark current obtained by adding barrier layer is one order of magnitude lower than the one without barrier l...