Silicon p-i-n photodiode with reduced crystallographic defect density and structured surface

Abstract This paper reports new methods for reducing the density of structural defects on the surfaces of silicon p-i-n photodiodes (PDs). We experimentally proved that removing the silicon layer with packing defects, which are formed during oxidation, significantly contributes to reducing the density of the dislocations generated after phosphorus diffusion. Compared with the classical diffusion-planar technology for the preparation of silicon-based p-i-n PDs, our methods improve the parameters of PDs, especially dark current, sensitivity, noise equivalent power etc. Removal of the silicon layer is realized by carrying out chemical-dynamic polishing of the wafers after thermal oxidation in the areas of responsive elements. Although the optimum thickness of the etched silicon layer is about 2 μ m, which corresponds to an etching time of 30 s, even taking into account the fact that the detector properties will deteriorate with increasing etching time, the change in the ‘maximum spectral response’ is positive. It is demonstrated that the chemical-dynamic polishing is a powerful tool to modify spectral characteristics of PD sensitivity. The maximum of the spectral response can be accurately tailored in a wide spectral range from by changing the chemical-dynamic polishing parameters.