A very few early semiconductors were packed in miniature evacuated glass envelopes, like flashlight bulbs; such expensive packaging was made obsolete when surface passivation and improved manufacturing techniques were available.
12.
The states cannot be removed by surface passivation if it does not break the time-reversal symmetry, which does not happen with potential and / or spin-orbit scattering, but happens in case of true magnetic impurities ( e . g . spin-scattering ).
13.
By superior layout and circuit design made possible by Bresee's and Khadders superior process uniformity, transistor performance, and surface passivation, Erdi was able to design and achieve breakthrough advances in micro power amplifiers with both low input offset and 1 / f noise voltage rivaling many chopper amplifiers formerly used exclusively for micro volt input amplifiers.
