An in-situ spectroscopic ellipsometer has been equipped on a molecular
beam epitaxy system to improve control of HgCdTe growth. Using this d
evice, in-situ analysis of composition, growth rate, and surface clean
liness were monitored. A real time model which determined the composit
ional profile was used. The ellipsometer was employed to give in-situ
real time control of the growth process.