Charge storage effects in p-n junction - Schottky barrier hybrid diodes

The influence of metal barrier height and diffusion profile on the charge storage characteristics of p-n junction guard ring or "hybrid" Schottky barrier diodes is discussed and examined experimentally. It is shown that the use of high barrier height metals, such as gold or platinum silicide on n-type silicon can severely limit high speed device operation at high forward current levels, due to minority carrier injection by the p-n junction. It is further shown that essentially majority carrier operation (i.e., no charge storage effects) can be maintained at high drive levels with the use of lower barrier height metals in combination with properly controlled surface concentration of the diffused p-type guard ring.