Controlled Surface Contamination to Determine Surface Sensitivity of HVICS

We report a technique that allows one to deposit on devices a controllable level of contamination as low as 108 atoms/cm2. Using this technique we were able to determine that surface contamination alone does not lead to reduced breakdown voltage of our high voltage PIN diodes. Good devices are essentially immune to surface contamination; however, "bad" devices are very sensitive to contamination. Contamination on the order of 1010 atoms/cm2 reduces the breakdown voltage of a defective diode by over 100V. We have proposed one possible model which describes the dependence of the breakdown voltage of a high voltage device on the applied bias, concentration of contamination, and field plate design. This model is based on the double layer theory of ionic solutions.