Method for fabricating planar avalanche photodiode array

摘要

A method of forming a planar photosensitive device, such as an array of APDs, includes the steps of doping a substantially planar block of n type semiconductor material with a p type dopant in accordance with a selected pattern to form a plurality of p type wells in the block surrounded by a foundation of n type semiconductor material. Each p type well corresponds to an APD pixel and is disposed so as to respectively adjoin a first surface of the block and such that a respective p-n junction is formed between the p type material in the well and the n type material foundation. Each APD pixel further comprises depletion layer profile modification means such that the peak surface electric field of the p-n junction in each well is substantially less than the bulk electric field of the same p-n junction. One type of depletion layer profile modification means is an peripheral doped region of p material disposed around each respective well; an alternative depletion layer profile modification means is a respective isolation moat around each well so as to separate p type material in the well from n type material in the foundation except along a parallel plane segment of the p-n junction.