Flicker noise in mos and bjt

dear all
why is flicker noise lower in bjt then in mos, and lower in pmos than in nmos ? dows anyone have a paper or ebook describing this issue in details...?

thank you very much 8)

An extensive flicker noise (pink noise) research paper can be located at:
http://www.bell-labs.com/org/physica...pubs/sam01.pdf

Flicker noise is low frequency noise caused due to traps for the charge carriers. For MOS due to the oxide layer interface lots of empty spaces/ vacancies are present which can act as traps and hence more the probability of the charge carrier to trap in MOS. BJTs have no such interface and the only traps are due to the internal vacancies inside the semicondutor