Antireflection Layer Coating for the Red Light Detecting si Photodiode

Abstract

The effect of antireflection layer on the reduction of optical loss has been investigated in Si photodiodes detecting red light with central wavelength of 670 nm. The theoretical analysis showed minimum reflection loss of 6% for the thickness of about in the -Si system with the single antireflection layer and no reflection loss for the XNthickness of / in the -Si system with double antireflection layer. In our experiments, Si photodiodes with the web-patterned -shallow diffusion region were fabricated by bipolar IC process technology and the devices were classified into three kinds according to the structure of /antireflection layer. The fabricated devices showed maximum spectral response in the optical spectrum of 650∼700 nm. The average photocurrents of the devices with the thickness of /X, and under the incident power, of -17 dBm were 3.2 uA, 3.5 uA and 3.1 uA, respectively.