REFLECTANCE-DIFFERENCE SPECTROSCOPY OF GAAS-SURFACES DURING OMCVD AND MBE CRYSTAL-GROWTH

Reflectance-difference spectroscopy (RDS) is used to compare (001) GaAs surfaces during MBE and atmospheric-pressure OMCVD growth. While some similarities occur, no direct parallel can be drawn. However, time, temperature, and pressure dependences of surface coverages by Ga-containing reacted species in OMCVD show that kinetically limited growth rates are determined by a combination of reversible excluded-volume chemisorption (at - 26 kcal/mole) and subsequent irreversible decomposition (at 39 kcal/mole) of trimethylgallium at (001) surface lattice sites. Our model explains the wide range of activation energies reported in the literature.