1. Rapid Thermal CVD of Si1-xGex
RTCVD of Si1-xGex using Si2H6-GeH4 chemistry (470oC~550oC)
Minimize diffusive mixing at interfaces using temperature and gas switching
Need process optimization to get the quantum dots or to deposit a Ge-graded film
DOE(Design of experiments)
3 factors : Temperature, flow rates of GeH4 and flow rate of Si2H6.
Responses : Growth rate, Ge concentration in films, and Morphology (dot size and density)
Full factorial with 3 center points
Neural network modeling
Using Bayesian Network
AFM (Morphology)
Dot density ( on Si > on SiO2 )
XRD (Ge concentration and thickness)
Ge composition ration and growth rate mainly
depend on the reactant ratio (PGeH4/PSi2H6 )
on SiO2
on Si
12.68%
17.75%
Ge 20.48%
Sung Bo Hwang The University of Texas at Austin